Maintec Variable Catback Exhaust Install

Draco-REX

Registered Member
95
178
33
Ohio
Genesis G70
I just installed the Maintec Variable Catback and I thought I'd make a full post about it since it's a bit more complex than most catbacks. Additionally, I would think that the other valved exhausts available may share some basics.

TL;DR, It's a great exhaust if you want to be able to switch between stock levels of volume and a more aggressive sound. The instructions are poor however.

I'll be writing this in 3 parts: 1. Explaining the box contents and supplementing the instructions. 2. My installation and what I chose to do. 3. My thoughts on the completed system.

Part 1. The box contents and Instructions.

The box comes with almost everything you need to install the catback. You will need two bolts, and at a minimum an inline fuse.

The exhaust parts:
The Midpipe has twin resonators and an X-Pipe connection like stock.

There looks to be good penetration of the welds, maybe a hair too much, but overall I think this is a well built system.

I thought I had taken pics of the mufflers, but I can't find them so I guess I didn't. I did however take closeups of a vacuum actuator and the tip.

These default to closed, meaning a quieter startup. I didn't test it, but it *MAY* be possible to rotate the assembly 90 degrees for it to default to open. But again, that's completely unproven. Also, one of the brackets was bent slightly. (The box did not ship well, as you'll see some small dents elsewhere on the system.) I noticed that one of the actuators was difficult to move which led me to discovering the bent bracket. It was easy to correct by just grabbing the actuator and bending it back to straight.


The tips come as bare metal, so they will be visible from behind until they get covered in soot.

The kit also includes the bolts and gaskets needed to connect the muffler sections to the midpipe. The two bolts you will need to get are for attaching the stock brace between the muffler sections. The stock mufflers use studs, so you'll just need to take off one of the nuts and hit up a hardware store to match the bolts needed.

For the electronics, you get a remote switch and a vacuum solenoid. Unfortunately, you only get instructions in Korean for these parts, and I don't have the benefit of being able to read Korean. So after sitting down with an old battery and a multimeter, here's what I figured out:

The Switch:

This switch has one positive (red) and ground (black) to supply power for itself, and a second part of wires (both brown) that are switched by the box. Connect the red wire to a positive power source and the black to a ground on the chassis. Then connect one brown wire to a positive power source and the other to the solenoid. The other wire from the solenoid gets connected to ground.

For the positive power source, I would highly recommend an inline fuse. Both the switch and the solenoid draw a very small amount of power, so a small 5Amp fuse will be fine.

The Solenoid:

There are three ports on the solenoid. One port comes with a length of vacuum hose and a clear check valve. This part gets connected to a vacuum source coming off the intake. The port at a 90 degree angle from the vacuum source is where you connect the line from the exhaust actuators near the mufflers. The last port is open to the atmosphere to let the valves re-open.

Also included is a length of (bright blue!) vacuum hose and 2 t-fittings. One T is for connecting to a stock vacuum line, and the second is to split the vacuum line you run to the back of the car so you can connect to the both valve actuators.

With this, it's possible to get the system installed and working. But the devil is in the details, and I did make quite a few changes. I'll talk about what I changed and why in part 2.
 

Draco-REX

Registered Member
95
178
33
Ohio
Genesis G70
Part 2A: My Install.

The exhaust installation itself was very straightforward. I did however fix the shiny tip issue before installing:

I didn't want the tips to be visible from behind the car, and I wasn't going to wait for soot to build up and hope it looked even. Just a little bit of flat black engine paint and they're ready to go on.

Out with the old:


In with the new:



I actually set up the electronics and front vacuum lines before putting in the exhaust, but the main line that runs the length of the car can be done with the exhaust. I ran it down the back of the engine across the front subframe to the passenger side and back between the underpanels and the floor pan. At the back of the car I ran it up over the rear subframe and then split it there to connect to the valve actuators.


If you look closely you'll see some spring clamps on the lines. The nipples on the actuators are so short that I wanted to be absolutely sure that the hoses wouldn't come off.

You'll also notice that the vacuum line is black, not BRIGHT BLUE. I wanted this to look more OEM-like, so I picked up some 5/32" vacuum line from my local autoparts store. I bought 24' and used most of it.

Now for the hard part:

The first thing I did was set up the vacuum solenoid. I figured it would be easier to route any needed wires (especially since I bought extra wire) than vacuum lines, so I tackled that first. The initial problem is where to tap into the vacuum system. Most of the hoses are FAR bigger than the vacuum line I was working with. There are fittings that can reduce the size of the lines, but I wanted a clean install. There is one line that is just the right size. If you follow the line from the turbo recirculating ("blow-off") valves, it will lead you up to the intake manifold. Where it connects initially looks like a heimholtz resonator, but after further inspection it turns out it's a vacuum reservoir. I'll go over what I think the reasoning for this is in Part 3. But for now, I want to tap into the line that feeds that reservoir so I don't interfere with how those recirc. valves operate. That line is the grey one in the red circle below:


Here's a close-up of that grey line, including the check valve that makes sure the vacuum reservoir doesn't see boost.


Since I don't want to interfere with that reservoir, I want to connect between the check valve and the intake, not after the check valve. So I use a short length of vacuum hose, a T, then connected the grey hose and then ran a new line under the intake to where I mounted the solenoid.


Because I want this to look more OEM, that clear check valve and blue line were out. Remember that grey line with the check valve? I bought another to use myself.

With check valves of this type, it will have an arrow on it that will indicate the airflow direction it allows. To keep it simple, the arrow should point towards the line that leads to the engine.

Also, I was not happy about having part of the vacuum system open to the elements. Most automotive vacuum solenoids come with a filter on them, but the one supplied with the kit did not. I found a filter that's actually used as a fuel filter for chainsaws. A bit of vacuum line and a small zip-tie and problem solved.


So here's the solenoid install, including the OEM check valve. I removed the Maintec bracket from the solenoid and ziptied it to the engine lift bracket behind the intake. You can just see the chainsaw filter right behind the intake too. I wanted it to be hidden from view and protected under the engine cover.

In this picture, the line to the exhaust valves isn't hooked up. Also the red/black wires are there because I had
the original switching box installed just enough to make sure everything worked.
 
Last edited:

Draco-REX

Registered Member
95
178
33
Ohio
Genesis G70
Part 2B: My Install

With the solenoid in place, it is time to get the electronics set up. In general, I was NOT happy with the remote switch that came with the kit. The biggest problem I had with it was that the circuit board was exposed to the elements. That isn't a big problem if I was willing to mount it inside the cabin. But after looking under the dashboard, I wasn't happy with what it would take to get a wire through the firewall. A second thing that, while not a big deal, I didn't really like was the fact that the remote only had 1 button. This made it tough to be sure what mode the system was in because at idle there's very little difference in volume level between open and closed. I replaced it with a different switch that was more closed and had a 2 button remote, so On is always open and Off is always closed.
DONJON Wireless Remote Switch
This fit most of the bill. But to be sure it's weather resistant, I opened the case and used some dielectric grease around the seams and over the contacts. This switch is a little bit different from the one in the kit in how it connects. This takes a power and ground to power both itself AND the solenoid. So the two output wires both go to the two solenoid wires. The solenoid does not go to ground itself.

I also wanted to cleanly connect to a switched circuit. The G70 uses new MICRO2 fuses that are very tiny. Thankfully, they make a MICRO2 add-a-circuit.
Lumison ADD-a-circuit
One thing to keep in mind is that depending on how you use these, you may end up losing power if the main circuit you're tapping blows. To keep that from happening you need to be sure the prong indicated below is put into the power side of the original fuse socket.


Where to put this is the next big question. Poking around the underhood fusebox there are a lot of fuses that you can choose, and points you can tap. But most of them are always powered. While the switch won't likely draw all that much power, I do want it to be powered off when the car is off. I was about to give up when I noticed that the two blank spots above the 10A spare had contacts in them. One was always powered, but the other was switched on/off with the car!

Making sure I was inserting the tap so the proper prong was inserted into the hot side, I left out the botton fuse on the tap, and I now had a switched power supply for the remote switch box.

Finally, to make it more OEM like, I used a weatherpack connector between the solenoid and the firewall.
Weatherproof Connector Pack

Assembled:


Take out three clips and move this piece of moulding aside:


Tuck the box up under the cowling and zip-tie it in place. Then remove a fourth clip to lift up the edge of the cowling a little and run the wires.

I dressed up the wires with some cloth tape, again to make it look OEM.

Then put it all back together:

If I did it right, it should fool an untrained eye.
 
Last edited:

Draco-REX

Registered Member
95
178
33
Ohio
Genesis G70
Part 3 Impressions: (Videos forthcoming. It's just too rainy right now for a good recording.)

As far as the install goes, the electronics could use improvement. But the exhaust itself was excellent. I have installed a ton of aftermarket exhausts, and this is the first one that I bolted up and it passed the shake test first try, no adjustments needed.

Switching between open and closed is quick and easy with the remote. But it did lead me to realize something about this car. While on the throttle, even just rolling down the road normally, those tiny little turbos are almost always generating some boost. The system won't switch from closed to open while you're on the throttle because of this. This also brings to light why Genesis designed that vacuum reservoir for the bypass valves. But this is easy to fix by just lifting your foot off the gas for a second or so then getting right back on it.

Now my main reason for getting a valved exhaust was because I leave my house at 5:40am every morning, so I didn't want my neighbors to hate me. Additionally, I wanted to use this car for long road trips, so a loud exhaust would have been really annoying, not to mention it would have failed the Wife test and we'd be driving her Tiguan everywhere.

Did the exhaust meet my expectations? Yes. With the valves closed volume levels are right at stock. In some ways it's even a bit quieter! The tone of the exhaust is more noticeable, but like the stock exhaust, it's easy to down out with the slightest bit of music or conversation.

Here's what I measured:
Stock Exhaust Cold Start: 61db
Maintec Exhaust Cold Start: 60db

Stock Exhaust Highway: 64db (Sport Mode, Enhanced)
Maintec Exhaust Highway Closed: 64db (Sport Mode, Enhanced)
Maintec Exhaust Highway Open: 68db (Sport Mode, Enhanced)

Now db levels aren't the whole story. Certain tones will be more noticeable than others. You can hear the closed exhaust slightly more than stock even though it isn't any louder. But as I mentioned before, it's just as easy to ignore or drown out. I didn't bother to take volume readings at WOT. With the valves closed you can definitely hear the difference. Valves open and it's a whole different car. It sound even better with the windows down. I'm looking forward to some actual nice weather so I can full appreciate the new sound.

Overall, I'm very happy with the exhaust. It was a fun project to install, and I'm looking forward this summer so I can fully enjoy the new sound.
______________________________
 
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Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,251
4,316
113
Genesis G70
Outstanding. As of writing this I've only read parts 1 and 2, but it's easy to tell you've done an excellent job with both documenting and the install.

The Maintec system looks very nice, especially the fact that it has a PROPER x-pipe! I like it.

Excited to read the rest of the install once you finished the posts.
 

Husky

Registered Member
790
757
93
Genesis G70
Wow! Great write-up, thanks. Well written, great detail, great photos. You did a really professional job on the install, and taking the sound level data.
The welds look very nice. Really a good looking exhaust system, glad it all fit properly, that is unusual. Also very considerate of you to think of your neighbors in choosing the system. Smart not to annoy them.
Enjoy!
 

Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,251
4,316
113
Genesis G70
If I were to go with any other exhaust system, I think this is the one I'd get. Speaking of Maintec, I've heard that they actually make, by far, the majority of aftermarket exhaust parts for all Genesis and Kia cars in Korea. In fact, other companies (eg Lap3) actually use their products then label them as their own.
 

Husky

Registered Member
790
757
93
Genesis G70
How do the pipe diameters compare to stock?
I assume they don't have that pinch point under the rear axle shafts.
______________________________
 

Husky

Registered Member
790
757
93
Genesis G70
Part 2B: My Install

With the solenoid in place, it is time to get the electronics set up. In general, I was NOT happy with the remote switch that came with the kit. The biggest problem I had with it was that the circuit board was exposed to the elements. That isn't a big problem if I was willing to mount it inside the cabin. But after looking under the dashboard, I wasn't happy with what it would take to get a wire through the firewall. A second thing that, while not a big deal, I didn't really like was the fact that the remote only had 1 button. This made it tough to be sure what mode the system was in because at idle there's very little difference in volume level between open and closed. I replaced it with a different switch that was more closed and had a 2 button remote, so On is always open and Off is always closed.
DONJON Wireless Remote Switch
This fit most of the bill. But to be sure it's weather resistant, I opened the case and used some dielectric grease around the seams and over the contacts. This switch is a little bit different from the one in the kit in how it connects. This takes a power and ground to power both itself AND the solenoid. So the two output wires both go to the two solenoid wires. The solenoid does not go to ground itself.

I also wanted to cleanly connect to a switched circuit. The G70 uses new MICRO2 fuses that are very tiny. Thankfully, they make a MICRO2 add-a-circuit.
Lumison ADD-a-circuit
One thing to keep in mind is that depending on how you use these, you may end up losing power if the main circuit you're tapping blows. To keep that from happening you need to be sure the prong indicated below is put into the power side of the original fuse socket.


Where to put this is the next big question. Poking around the underhood fusebox there are a lot of fuses that you can choose, and points you can tap. But most of them are always powered. While the switch won't likely draw all that much power, I do want it to be powered off when the car is off. I was about to give up when I noticed that the two blank spots above the 10A spare had contacts in them. One was always powered, but the other was switched on/off with the car!

Making sure I was inserting the tap so the proper prong was inserted into the hot side, I left out the botton fuse on the tap, and I now had a switched power supply for the remote switch box.

Finally, to make it more OEM like, I used a weatherpack connector between the solenoid and the firewall.
Weatherproof Connector Pack

Assembled:


Take out three clips and move this piece of moulding aside:


Tuck the box up under the cowling and zip-tie it in place. Then remove a fourth clip to lift up the edge of the cowling a little and run the wires.

I dressed up the wires with some cloth tape, again to make it look OEM.

Then put it all back together:

If I did it right, it should fool an untrained eye.
What is the vacuum line used for - to sense WOT or to actuate the valve?
I guess I'm wondering if it opens automatically or under control electrically, or both.
 

OMG70

Master Bruce!
1,308
1,494
113
LA/OC, California
Genesis G70
You measured decibels from inside the car on the highway or was there something clipped/mounted outside? Because wouldn't "Enhanced" just pump in fake exhaust noise from the speakers?

Nonetheless, great guide and write up!
 

Draco-REX

Registered Member
95
178
33
Ohio
Genesis G70
How do the pipe diameters compare to stock?
I assume they don't have that pinch point under the rear axle shafts.
They are slightly larger and don't have any of the pinch points. It's all smooth mandrel bends.

What is the vacuum line used for - to sense WOT or to actuate the valve?
I guess I'm wondering if it opens automatically or under control electrically, or both.
Vacuum is used to open the valves. The electronic box controls whether the actuators are exposed to the engine's vacuum or not. Once open they stay open until the solenoid is turned off.

You measured decibels from inside the car on the highway or was there something clipped/mounted outside? Because wouldn't "Enhanced" just pump in fake exhaust noise from the speakers?

Nonetheless, great guide and write up!
The cold start db were measured from about 10ft behind the car. The highway db were measured from the driver's seat. I set the car in Sport Mode and Enhanced to create a worst-case scenario. At cruise there is very little, if any, pumped-in exhaust note.
 

CVODON

Registered Member
111
58
28
Genesis G70
You did an absolutely great job of documentation in this install. Sure it took extra time to photo & write the details and you definitely took the time and made the effort.
______________________________
 

petraman

All Gas, No Brakes
123
159
43
Genesis G70
Great write-up! One thing I've been curious about with these aftermarket valved exhaust systems... Can you set Homelink to operate it?
 

petraman

All Gas, No Brakes
123
159
43
Genesis G70
Looking forward to hearing the results! BTW, where in Ohio are you? Here in Columbus, I've seen exactly one other G70 on the road.
 

RonE_RRTX

Hasn't posted much yet...
SUSTAINING MEMBER
I just installed the Maintec Variable Catback and I thought I'd make a full post about it since it's a bit more complex than most catbacks. Additionally, I would think that the other valved exhausts available may share some basics.

TL;DR, It's a great exhaust if you want to be able to switch between stock levels of volume and a more aggressive sound. The instructions are poor however.

I'll be writing this in 3 parts: 1. Explaining the box contents and supplementing the instructions. 2. My installation and what I chose to do. 3. My thoughts on the completed system.

Part 1. The box contents and Instructions.

The box comes with almost everything you need to install the catback. You will need two bolts, and at a minimum an inline fuse.

The exhaust parts:
The Midpipe has twin resonators and an X-Pipe connection like stock.

There looks to be good penetration of the welds, maybe a hair too much, but overall I think this is a well built system.

I thought I had taken pics of the mufflers, but I can't find them so I guess I didn't. I did however take closeups of a vacuum actuator and the tip.

These default to closed, meaning a quieter startup. I didn't test it, but it *MAY* be possible to rotate the assembly 90 degrees for it to default to open. But again, that's completely unproven. Also, one of the brackets was bent slightly. (The box did not ship well, as you'll see some small dents elsewhere on the system.) I noticed that one of the actuators was difficult to move which led me to discovering the bent bracket. It was easy to correct by just grabbing the actuator and bending it back to straight.


The tips come as bare metal, so they will be visible from behind until they get covered in soot.

The kit also includes the bolts and gaskets needed to connect the muffler sections to the midpipe. The two bolts you will need to get are for attaching the stock brace between the muffler sections. The stock mufflers use studs, so you'll just need to take off one of the nuts and hit up a hardware store to match the bolts needed.

For the electronics, you get a remote switch and a vacuum solenoid. Unfortunately, you only get instructions in Korean for these parts, and I don't have the benefit of being able to read Korean. So after sitting down with an old battery and a multimeter, here's what I figured out:

The Switch:

This switch has one positive (red) and ground (black) to supply power for itself, and a second part of wires (both brown) that are switched by the box. Connect the red wire to a positive power source and the black to a ground on the chassis. Then connect one brown wire to a positive power source and the other to the solenoid. The other wire from the solenoid gets connected to ground.

For the positive power source, I would highly recommend an inline fuse. Both the switch and the solenoid draw a very small amount of power, so a small 5Amp fuse will be fine.

The Solenoid:

There are three ports on the solenoid. One port comes with a length of vacuum hose and a clear check valve. This part gets connected to a vacuum source coming off the intake. The port at a 90 degree angle from the vacuum source is where you connect the line from the exhaust actuators near the mufflers. The last port is open to the atmosphere to let the valves re-open.

Also included is a length of (bright blue!) vacuum hose and 2 t-fittings. One T is for connecting to a stock vacuum line, and the second is to split the vacuum line you run to the back of the car so you can connect to the both valve actuators.

With this, it's possible to get the system installed and working. But the devil is in the details, and I did make quite a few changes. I'll talk about what I changed and why in part 2.
@Draco-REX - You mentioned 2 bolts needed -" The kit also includes the bolts and gaskets needed to connect the muffler sections to the midpipe. The two bolts you will need to get are for attaching the stock brace between the muffler sections. The stock mufflers use studs, so you'll just need to take off one of the nuts and hit up a hardware store to match the bolts needed" do you happen to know the size of these? I would like to have them in-hand before getting started.
 

Draco-REX

Registered Member
95
178
33
Ohio
Genesis G70
@Draco-REX - You mentioned 2 bolts needed -" The kit also includes the bolts and gaskets needed to connect the muffler sections to the midpipe. The two bolts you will need to get are for attaching the stock brace between the muffler sections. The stock mufflers use studs, so you'll just need to take off one of the nuts and hit up a hardware store to match the bolts needed" do you happen to know the size of these? I would like to have them in-hand before getting started.
Unfortunately, no. I just took one and matched it. Sorry.
 
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