Aftermarket Exhaust Choices

[Rey]

It appears there are but two choices: Borla and MagnaFlow. Borla is more expensive. Borla features flange joints. MagnaFlow has slip-on joints. Borla has straight unconnected pipes from the rear cats to Borla's rear mufflers. MagnaFlow also has a straight pipe section, but within it there is an "X-pipe crossover" connector.
I did some sound comparisons with U-Tube footage; and concluded that Borla is louder with a raspy sound. X Pipes are known as an effective sound attenuator, which produces a modest power gain over unconnected pipes.
I decided to go with the MagnaFlow on the basis of pricing and the fact that MagnaFlow has a bit more mellow sound. I didn't want quite the sound level. I am a geezer and am hard of hearing, but nevertheless a droning sound is bothersome to me.
So I have modified the MagnaFlow to quiet it down a bit with no material decrease in performance. What I did was to mount a MagnaFlow X-muffler where the MagnaFlow X-pipe is located. The muffler I used was MagnaFlow #11386 available at Summit Racing for a bit less than $100, shipping included.
I think there is room for a larger muffer like the Dynomax 17553, which is also an X design.
So far, I note a nice quiet idle and low noise level at steady-state or light acceleration. There is a brief drone when lugging the motor at around 1400 rpm, which may require some more attention. Of course, at WOT it gets noisy.

 

[yuhaze]

I got the Borla and LOVE it! Admitted, it took me quite some time to enjoy it. It took a few hundred miles for the note to "settle"
Now it is awesome, I'm glad I spent the extra $$

 

[msitter]

I like the throaty sound of a V8 engine but I have been hesitant to do anything about the quiet of the Genesis exhaust system. I have replaced several on other cars and have gotten that great sound except every one of them also had that annoying drone at steady highway speeds and I really don't want to chance that on the Genesis.

 

[robthoke]

I've got a Magnaflow system on mine and I love the sound as do many of the people who ride with me. You do have a couple of years on me though. I also have the dual mode muffler system on the wife's Vette and we run with that open all the time as well. It is much louder than the Genesis.

 

[Rey]

I have about 1000 miles now on my "Modified MagnaFow" system. I am very happy with it. Sound is just a bit muted from the stock MagnaFlow. However, there is still an annoying drone when lugging at low speed.
I have done a bit of research on aftermarket exhaust drone. It appears to be a common problem with low back pressure exhausts. GM has worked out an option for Corvette owners which retains back pressure and sound attenuation at low rpm but opens the exhaust at high rpms. I am over simplifying the principle for the sake of brevity, but I direct you to the LS Tech sites for more detail.
In June 2010 Dynamax introduced the VT muffler, which is dual tone design. A spring loaded flap partially restricts exhaust at low speeds causing exhaust sound (drone) to attenuate. At high speeds the flap opens. The result is much like the optional Corvette exhaust system. I have ordered these mufflers and will install them in April.
Now that I have had a chance to examine the OEM exhaust system off the car, I think were I to modify my exhaust again I would do a simple exhange of the rear mufflers for the Dynamax VT. Both MagnaFow and Borla offer 2.5" exhaust piping. OEM is 2.25". I don't think the added diameter of aftermarket systems is all that big a deal. The stock system has its limitations. There is a serious 4" long crimp to the OEM pipe between the rear cat and the central resonator. This can be cut out fairly easily. The central resonator is pretty efficient with a straight-through design. There is also a connection between exhaust pipes within the central resonator. The major plug to the system is the huge rear mufflers.

 

[msitter]

I have been looking at the VT mufflers as well. One thing that bothers me about them however is the low rpm rattle that several on other sites posters noted. Dynomax has been good to honor the warranty but do you really want to change mufflers that often? I think I will keep a close eye on the posts and when the rattle seems to have been fixed I will consider them. I guess the rattle comes from the spring loaded flapper valve inside the muffler that is blown open when the exhaust pressure builds during acceleration.

 

[sambeaux]

I picked up the magnaflow used from a guy on this forum. Even though I got an awesome deal on it, I must say I'm not happy with it. Im on the other end of the age spectrum of most of you at 23 and was hoping it was going to be more aggressive. I'm currently looking into other options, maybe cutouts or replaceing the magnaflow mufflers. I might even do the unthinkable and install a pair of flowmasters!

 

[robthoke]

I picked up the magnaflow used from a guy on this forum. Even though I got an awesome deal on it, I must say I'm not happy with it. Im on the other end of the age spectrum of most of you at 23 and was hoping it was going to be more aggressive. I'm currently looking into other options, maybe cutouts or replaceing the magnaflow mufflers. I might even do the unthinkable and install a pair of flowmasters!

Try Cherrybombs. They've been distrubing the peace for years (or so they say).

 

[Rey]

I also read posts complaining about the flapping valves on VT mufflers. It appears that these complaints arose with first-produced mufflers that were not properly sized for the particular application. At least one of the posters tried a different size muffler which eliminated the flapping valve. I think most of these complaints were with large 3" exhaust systems and heavily cammed motors which sent out pulsing exhaust flows at idle.
Whatever, I will not be able to install my VT mufflers until after April 15th, at which time I will post again on this subject. Presently, I have the mufflers. They appear to be very robust. Dynomax claims that at WOT they outflow many competitors' mufflers. I can see that when the flap opens there is a simple straight-through flow glass-pack design.

 

[Chief]

Try Cherrybombs. They've been distrubing the peace for years (or so they say).

They aren't lying. I had on my 1967 396 Camaro.

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[bradyb]

It appears there are but two choices: Borla and MagnaFlow. Borla is more expensive. Borla features flange joints. MagnaFlow has slip-on joints. Borla has straight unconnected pipes from the rear cats to Borla's rear mufflers. MagnaFlow also has a straight pipe section, but within it there is an "X-pipe crossover" connector.
I did some sound comparisons with U-Tube footage; and concluded that Borla is louder with a raspy sound. X Pipes are known as an effective sound attenuator, which produces a modest power gain over unconnected pipes.

I have the borlas cat-back exhaust. here are some details that you left out. the Borla does have a cross-over included in the design. Also this system eliminates the crush points on the stock exhaust tubes just behind the flange. System also is designed with Borla's patented XR-1© multicore muffler technology. this minimizes drone because it is custom tuned to the car. the mufflers have been custom made just for this car. The package is good for 22 wheel torque increase and 17 wheel hp increase (on the dyno)

http://www.borla.com/products/product_detail.aspx?prod_sku=140377 BTW the car pictured is mine! Ive always been a fan of dyno-max/magnaflow muffs. Im not sure I would have thrown out the clams for the Borla system without driving it, I probably would have gone to a custom muffler shop! After driving it Im very impressed.....

I've also got some sound DB measurements in threads. PM me if anyone has questions......

 

[NoMids]

I also read posts complaining about the flapping valves on VT mufflers. It appears that these complaints arose with first-produced mufflers that were not properly sized for the particular application. At least one of the posters tried a different size muffler which eliminated the flapping valve. I think most of these complaints were with large 3" exhaust systems and heavily cammed motors which sent out pulsing exhaust flows at idle.
Whatever, I will not be able to install my VT mufflers until after April 15th, at which time I will post again on this subject. Presently, I have the mufflers. They appear to be very robust. Dynomax claims that at WOT they outflow many competitors' mufflers. I can see that when the flap opens there is a simple straight-through flow glass-pack design.

Hi Rey,

Have you had the new mufflers installed? What are your impressions.

Thanks for the update,

Tom

 

[Rey]

I now have 6000 miles on the Dynomax VT mufflers. Install was a bit tricky. I have an excellent exhaust guy who does a lot of custom work. It was almost impossible to center the outlets to the rear bodywork. We wound up canting the mufflers a tiny bit and using single large outlet canisters.

I am very pleased with the sound. The drone is almost completely gone. I can induce drone briefly, but only at lugging rpm. At usual light throttle acceleration and cruise the sound is OEM.