Custom exhaust ideas

[jcl78]

Hey all,

I have been bitten by the "SHO is too quiet" bug. Tell me what you all think of this idea:

I have had work done in the past for my WRX at a local exhaust shop, go there, have him fab up an H pipe to delete the mid-muffler, and replace the two mufflers with Magnaflow / Dynomax 14" mufflers and call it a day without touching the stock piping.

I know another member had a similar setup done, only with a fabbed up X pipe and piping back. I think an H-pipe would be fine for a twin turbo setup as scavenging post turbo isn't really necessary. I am hoping for a nice mellow growl.

[EcoBrick Bob]

I have an H pipe on one of my G8's and an X-pipe on the other.  The H-pipe is deeper throated, and louder at slow speeds, but quieter on the road, because note is lower and can't be heard as well.  It also seemed to have more low end torque when both had similar mods.

Aren't Dynomax mufflers aluminized vs SS?  If so, I would recommend SS Magnaflows, like I used on my Flex. Bought the satin ones and painted them black to look stock.  Also used stock tips.  Mufflers, & install was just over $300. back in 2010 in Naples, FL.

As far as an H pipe, if you start back of 3rd Cat, you can use it to replace the mid-muffler rather cheaply.  I bought mine from Nesho where it  had been fit to bolt in at front, and with extra flanges to mount at rear, both it, and stock section so I could replace.  Cost for all that installed was approximately $450.

[bnoon]

I'm going to go with a single stainless x-over muffler from Magnaflow. The x-pipe is inside the muffler. Once I get that on, I can see how loud it is and decide on rear mufflers if any.

[EcoBrick Bob]

Rear Muffler replacement is "Noise Fluff"!  Downpipes add HP/TQ. 

After getting the SCT tuner from Torrie, my next mod were the 2 rear Magnaflows.  The sound is similar to a  2011 or newer  V-6 Mustang.  PPE catted downpipes w/o Nesho mid-pipe are slightly louder at low speeds but not noticeable at HWY speeds.
My wife hasn't noticed the PPE pipes, and if the noise was noticeably louder she would have at least wondered what changed. She has "Tolerant but very sensitive ears"!  LOL

[jcl78]

Thanks Bob, I am not sure on the Dynomax  material, I will check it out. I like the sound of the Magnaflow's on another member's SHO, so sounds like I will go that route.

Oh and, noise fluff is all I want! I know this setup would yield no gains, just want to hear at least a little sound

[bnoon]

I have the catless PPE dp set with the stock second cat back and all I notice around town is an added whistle from the hair driers up front. Though people outside my Flex tell me there's quite a bit more noise outside under wot. I want that x-pipe Maglaflow in place of the second cat and 2.5" pipes to the rear to match the size of the PPE dps. Is there any power gains at all from the second cat on back with matching pipe size? Or is it ALL noise fluff?

[EcoBrick Bob]

Probably a small amount of power, most likely at the top end.  In guys with G8's long tubes either catless or free flow cats in larger diameter mid-pipe, the stock catsback mufflers made only a few HP less on the dyno, and were much quieter, not quiet like completely stock, but not obnoxious.

Stock Flex ( & think the same with SHO & Sport) exhaust is 2 1/4". 

Solution:  Electric Cutouts behind Downpipes!!!!

[jdeprato]

All I know is that when people put anything too loud on this car it sounds like crap. i.e. the Corsa matched up with catted or uncatted downpipes. This car definitely needs someone to come up with a nicely tuned solution that isn't obnoxious. Maybe I'm just more used to how my LS2 GTO sounds...

[EcoBrick Bob]

I can record one of my G8's and you can add a speaker between the rear pipes!

You are right about getting the exhaust too free flowing, and the V-6 sounds. That's why leaving stock rear mufflers and adding Downpipes, and possibly eliminating mid-muffler and 3rd cat  is less noisy, and gives you the best sound and performance.

Or... the cheapest way is just adding the two rear magniflows (nothing else) if just a bit of noise is one's goal.  Stock V-6 Mustangs sound really good for being 6 cyl., which is the sound the Magnaflows produce.

[pejohnson]

Which Magnaflow mufflers did you get?  I see the #15769 for the cat back system but just want the mufflers.

[shoman04]

Thanks Bob, I am not sure on the Dynomax  material, I will check it out. I like the sound of the Magnaflow's on another member's SHO, so sounds like I will go that route.

Oh and, noise fluff is all I want! I know this setup would yield no gains, just want to hear at least a little sound

JC I was the 1st here with the DynoMax muffler and I had a local shop build my 2.5 cat back sys with a Magnaflow x-pipe and the DynoMax muffler. They come with a 2.5" lip step down to 2.25" to fit the stock pipes. My shop cut the step down off and weld the 2.5" right on the Dynomax like they came that way!!!!! Down right grrrrrrreat!!!!!

[jcl78]

Thanks Shoman! That's right, it was you I was thinking of with the Dynomax.

I am still waffling on the idea. The SHO is such a sleeper right now, but I am wanting for more sound on most days. There is an excellent muffler shop close to me that I already have experience with, and I know it would not be terribly expensive to have them weld in the H pipe in place of the resonator and new mufflers. I just don't want it too loud all the time, just really when I get on it.

A tune is a go for December this year (the wife gave me permission ) so with that and some more sound out of the exhaust I will be happy.

[EcoBrick Bob]

I went to the Magnaflow site in early 2010 and picked out non-polished stainless mufflers that were oval, same pipe length & diameter and had the same in and out positions as the flex.  The muffler shop got them for me and installed for a total of around $300. using my tips.  I then painted them flat black to make them look stock.  Can't remember the part # of mufflers, but it should be easy to find on their site.

[shoman04]

Thanks Shoman! That's right, it was you I was thinking of with the Dynomax.

I am still waffling on the idea. The SHO is such a sleeper right now, but I am wanting for more sound on most days. There is an excellent muffler shop close to me that I already have experience with, and I know it would not be terribly expensive to have them weld in the H pipe in place of the resonator and new mufflers. I just don't want it too loud all the time, just really when I get on it.

A tune is a go for December this year (the wife gave me permission ) so with that and some more sound out of the exhaust I will be happy.

I have a deal with the wife. That for road trips I put the stock mufflers back on to make the SHO stock quite. But the x-pipe didn't add to the sound. And most local shop can not do Mandrel bent tube but look at my pipes. at the low rate of bents our exhaust. Not  have the non mandrel does not hurt you. Plus I pull 405awhp and 417 tor at LMS doing my MET tune. x-pipe $60(autoanything.com), 2.5"pipes $500 installed (taxes, labor, parts, materials ). Not back for a total cat back sys.

[EcoBrick Bob]

Nice dance moves shoman04!!!  Just noticed!