Borla exhaust for R-Spec... should I do it?

[Skywagon]

Rey,
Thanks again. I'm 98% sure it's 2.25 inch pipe throughout. I hope to have some wheels put on this week and will take a micrometer to the exhaust, the entire length. I'll start on the exhaust as soon as MSA sends my cat deletes, or do you think it will be too loud without the secondary cats? I'd like to re-size the dimple plumbing, as you suggested, but I want to be able to go back to completely stock, if necessary, unless you think the HP gain is sufficient to warrant taking a torch to it.

 

[Rey]

Motorsports Authority claimed about a 6hp increase with the rear cat deletes.
On my 2009 and my 2011 that seemed about right. No material increase in noise with the cat deletes.
Yes, I think it is worth the effort to remove the dimples. This is something one would not have to undo if "restoring to stock", in my opinion. The dimples are a serious restriction.

 

[Skywagon]

Rey,
Understand, I'll remove the dimples. You are a wealth of knowledge.
Thanks

 

[Skywagon]

Rey,
One more question. To be 100% correct you have the Cat delete on your 4.6, still have the center muffler/resonator just behind the secondary cats locations and two Dynomax #17156 mufflers at the rear bumpers. However, you state you also have a modified Magnaflow system. Please explain. Also, if you were to rate the sound of your system to the stock system, on a scale of 1-10, stock being zero, what level would yours be? I'm not looking for a loud sound, just something I can hear, like about a 2-3?
Thanks much

 

[Rey]

I have a modified MagnaFlow system. I have deleted the rear cats, which attach to the 2.5" Magnaflow system. The "stock" MagnaFlow comes with an "X" pipe in place of the OEM central resonator. Aft of this are two mufflers. I discarded the X pipe and replaced it with a MagnaFlow X muffler. I never even ran it with the X pipe. I did not like the drone, but liked the mellow exhaust sound otherwise. Then I replaced the rear mufflers with Dynomax VTs, which are more quiet than the MagnaFlow and do not drone. The noise from inside the car is quite muted. At cruise it is just simply quiet as OEM. At more than light throttle you know you have a motor, but it is not obnoxious, and easily passes "The Wife Test".

 

[Hmma102752]

Rey....what exactly did u do so when I buy mine in a couple weeks I know what u did so I could have the same non drone sound as u.....thank man

 

[bradyb]

YUHAZE> whats up buddy? how ya doin?

Do it!

YES, YES, YES!

order the pipes, take them to the dealer, I paid < $40 for them to install, took minutes.
I have no clue where losing your vehicle for two weeks came from (reference to previous post in this thread)

 

[Skywagon]

Rey,
Thansk, very much, again. I just talked to the gents at MSA and they claim they'll build the Cat deletes today and ship. Hopefully I'll see them soon. I'm going to leave the stock resonator on the car. If I get the droning I'll go to an X pipe or X muffler.

 

[Rey]

Here is what I did:
1. Bought a MagnaFlow catback exhaust.
2. Installed Motorsports Authority rear cat deletes
3. Bought a MagnaFlow 2.5" dual in/dual out muffler #642-11386 from Jegs, and inserted it in place of the MagnaFlow's "X" pipe.
4. Bought two Dynamax #17156 VT mufflers.
This required custom exhaust work. In most cities there are people who still do such work. Fitting the rear mufflers took some ingenuity and the mufflers can be seen from the side of the car - a bit. Painted the mufflers flat black.
I am not so sure that the larger 2.5" aftermarket exhaust (Borla + MagnaFlow) produce all that much more power than an equivalent 2.25". So, on my new RSpec I will delete the rear cats; retain the center oem resonator; and then have my exhaust guy make up a complete exhaust aft with 2.25" VT mufflers (Dynomax 17155).

 

[Skywagon]

Rey,
Again, excellent info. Your statement concerning the visibility of the mufflers from the side is a little concern for me. I have a Platinum car and they may jump out a little. I know I've become a pain in the butt, but would you consider posting a couple of pictures of your install and the view from the side. When I do my wheels the car will be up on a hoist and I'll do some measuring of my diameters. I've got an excellent shop but your pioneering could reduce head scratching considerably.
Thanks very much

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[Rey]

I don't have very illustrative pictures; and I could not attach the pictures I dohave. Best you email me directly. I will jack up the rear of the car and take some photos to send to you. Reykirman@comcast.net

 

[Skywagon]

Rey,
E-mail sent.
Thanks

 

[Skywagon]

Rey,
E-mail kicked back. I'll send you a PM.

 

[NSXNEXT]

skywagon,

Make sure you post them in this thread. I think we're all interested in how these look.

 

[Dragon64]

The company we all need to contact is RACE PRECISION Inc.

They make the best sounding exhaust around - and for a great price

if they get enough interest - they WILL make a quad exhaust for the R Spec

 

[Rey]

In terms of just exhaust sound, Borla and MagnaFlow offer good starting points. I don't think it is necessary to employ another party for a complete cat-back exhaust.
As for a quad tip exhaust, I wonder how it might look inside the RSpec's comparatively small rectangular exhaust port?
Where I think there is some real power potential is in a long tube header. I am somewhat familiar with the 4.6 exhaust manifold, which is really a primitive design that looks like OEM '50s. I have heard the 5.0's manifold is a better design, and will check it out when my RSpec arrives in a few days.
Generally, all current manufacturers locate the primary cats right next to the exhaust manifold outlet. The reason is an EPA requirement that cats light up asap. Long tube headers move the cats to where our secondary cats now reside. California presently does not permit any modification (cat forward), even if overall emissions are not increased. So, Californians cannot have long tube headers.
My understanding is that Motorsports Authority considered creating long tube headers, but felt there just wasn't room. I wonder?
One header manufacturer that is known for doing small runs is American Racing Headers. I wonder if they'd be interested?

 

[Skywagon]

Rey,
I hope to do the exhaust this Friday, the 16th. As far as headers go, the big question would be where will the primary cats be moved to? My guess would be where the secondaries now are. Of course that requires new wiring. If not, someone would have to create an oxygen simulator to fake out the engine ECU or one would potentially have a constant "check engine light" which may eliminate the passing of a state inspection. What do you think?
Thanks

 

[Dragon64]

In terms of just exhaust sound, Borla and MagnaFlow offer good starting points. I don't think it is necessary to employ another party for a complete cat-back exhaust.
As for a quad tip exhaust, I wonder how it might look inside the RSpec's comparatively small rectangular exhaust port?
Where I think there is some real power potential is in a long tube header. I am somewhat familiar with the 4.6 exhaust manifold, which is really a primitive design that looks like OEM '50s. I have heard the 5.0's manifold is a better design, and will check it out when my RSpec arrives in a few days.
Generally, all current manufacturers locate the primary cats right next to the exhaust manifold outlet. The reason is an EPA requirement that cats light up asap. Long tube headers move the cats to where our secondary cats now reside. California presently does not permit any modification (cat forward), even if overall emissions are not increased. So, Californians cannot have long tube headers.
My understanding is that Motorsports Authority considered creating long tube headers, but felt there just wasn't room. I wonder?
One header manufacturer that is known for doing small runs is American Racing Headers. I wonder if they'd be interested?

Race Precision inc make a great exhaust - they have an excellent reputation - and I've used their product - so it's worth the time for the
R Spec ( and other ) members to show some interest - it gives everyone another option

I'm certain that they would develop an exhaust if enough members contacted them.

I'm not knocking Magnaflow or Borla - but there's more to life - and our cars - than just the two of them

There are some great clips of the RPI GT exhaust on YouTube for a whole host of cars- they are big with BMW

and have some great clips with the BMW 550i and the ///M5

 

[Skywagon]

Rey and all,
As beauty is in the eye of the beholder sound is in the ear of the same. Today I had MSA's cat deletes installed and cut out the resonator. We first checked out the sound after the secondary cats were removed. If one were to assign a value to the sound of the exhaust, stock being zero and straight pipes being 10 I'd say their removal increased the sound by a .5. Unfortunately, Rey, I was unable to use the Dynamax mufflers because we couldn't figure out how to fit them. It wasn't due to their size but because one has to use a offset in and offset out to match them up to the exhaust holes in the bumper. The stock mufflers are huge and fill a large area behind the rear wheel wells. If one can get a muffler that has the entrance and exit on the same side of the muffler it would probably work. The Dynamax muffler enters on one side of the end but exits in the center of the other. We then cut out the center resonator, did a little pipe bending on a machine and welded in the straight pipes. Also installed a couple of washers under the brace where the resonator used to be to insure clearance of the new pipes.
If one were to assign a value to the sound I'd give it a 3, which is what I wanted. Some may say the sound is too tinny? It is not a deep sound but one can certainly hear the exhaust. In all, with the cat deletes from MSA, the new tubing used, and all the cutting and welding the price came to about $325. The stock mufflers remain on the car. The good thing about this process is that it can be done in stages and the car is still relatively quiet. If one can find the right muffler then one can make the car louder to their liking. The center resonator is a straight through device with a perpendicular tube joining the two. Also, the plumging on the R-Spec is 2.25 inches I.D. through out.
Hope this helps.

Stock

Cat Deletes

Straight pipes

 

[Skywagon]

The below muffler may be just the thing. But will it produce the dreaded drone?

http://www.magnaflow.com/02product/shopexd.asp?zone=main&id=9287