2008 GT500 Exhaust Set Up

So the previous owners put on Kooks LT headers (not sure on size), 3" catted x-pipe, 3" tubing going into 3" Magnaflow Competition axle backs. This set up puts out crazy drone around 1800 - 2100 rpms. They also removed all the connecting point clamps and welded all the connections. The drone really limits the activities I can do with the family in the Shelby as its just too loud. Having 3" tubing really limits what axle back I can use as well.

So what I'm thinking of doing is downsizing and changing the set up to Kook's 3" to 2.5" catted H pipe, Dynomax 2.5" stock over axle pipes, and stock axle backs or whatever I like. Whats a good axle back? Does the 2.5" over axle pipes limit the power you can make?

Could I use 11-14 GT500 3" to 2.75" mid pipe, 2.75" over axle pipes, and will 11-14 GT500 axle backs fit in the right spot with the exhaust hangers?

You could try some resonators that should help with the drone and would be a lot cheaper than replacing the whole exhaust. $150 for two resonators
http://www.autoanything.com/exhausts-mufflers/mbrp-universal-resonators

MBRP has a street series cat back and its a 3" that will be a lot quieter. if you went that route. $450-600 for new cat back
http://www.autoanything.com/exhausts-mufflers/61A1966A0A0.aspx

The 13-14 axle backs require more than just a muffler swap.

Could try some resonators and see what happens. I also think I would like to have more axle back options

Corsa if you have the money.

If you feel like getting into a little design, look into side branch resonators (helmholz resonator). Use 2 different sizes of pipe at the end to slide over each other for fine tuning. Use trialware software on a laptop to find the frequency (wavelength) of the drone.
I don't think pipe diameter matters too much as its not flowing air, just sound.

FWIW a lot of folks who have headers usually go back to stock axle backs to quite it down some. If you need more then that resonators could be installed. I do not have LT but with my ORH and Borla tourings it is perfect.

Beercules said:

Corsa if you have the money.

If you feel like getting into a little design, look into side branch resonators (helmholz resonator). Use 2 different sizes of pipe at the end to slide over each other for fine tuning. Use trialware software on a laptop to find the frequency (wavelength) of the drone.
I don't think pipe diameter matters too much as its not flowing air, just sound.

Click to expand...

Yea I'm not trying to do all that. Wanting to keep it simple with tried and true set up's.

HillbillyHotRod said:

FWIW a lot of folks who have headers usually go back to stock axle backs to quite it down some. If you need more then that resonators could be installed. I do not have LT but with my ORH and Borla tourings it is perfect.

Click to expand...

That's what I've been seeing after a day of searching. Thinking of buying new Kooks catted 3" to 2.5" H-pipe, RockAuto sell's 2.5" over axle pipes for $38/each, and find some stock mufflers and go from there. Guess in all reality I just want a good set up with no drone.

I'm also not trying to make a 1000hp. From what I've seen stock 2.5" exhaust is good for what I'm trying to do which is stay under 700hp. May upgrade to a trinity later on.

I have a couple of summit racing 3" X 6" mufflers I used for resonators, just a touch raspy on wfo, good for cruising with no drone, I'm pretty much the same exhaust setup with MBRP competition mufflers

So RockAuto sell's an over axle pipe/muffler kit (Linked below). Does anyone know how those mufflers sound? Are they supposed to replicate the stock mufflers?

http://www.jegs.com/i/Dynomax/289/39414/10002/-1?ymm=4294829649+4294829830+4294829436

I am working on a similar exhaust project.

From what i can tell the 11-12 gt500 mufflers will work once you buy/install the 11-14 exhaust hangers. They bolt in.

Once you have those mufflers installed, you could run thge 2.75" over axle pipes along with the newer mid pipe.

Buy 2010 GT500 stock mufflers and just try just that first. They have 0 drone and are extremely driveable daily muffler but when you get on it they sound great. Its probably one of the best mufflers to come from the factory as far as limiting drone while not choking the car too much.

the 2010 GT500 are a direct bolt on, same hangar locations etc. Went from Corsas that made popcorn everywhere i went to those stockers and i couldnt be happier. They sound so clean

^^ that's a great idea but unfortunately they are only 2.5".

I want to convert mine to 2.75 or 3" from x-pipe back which is why i like the 11-12 gt500's.

gimmie11s said:

I am working on a similar exhaust project.

From what i can tell the 11-12 gt500 mufflers will work once you buy/install the 11-14 exhaust hangers. They bolt in.

Once you have those mufflers installed, you could run thge 2.75" over axle pipes along with the newer mid pipe.

Click to expand...

I read somewhere that the 10-14 GT500 mufflers stick out further than the 07-09 GT500. Something to think about. After a quick search it looks like I can get a 3" to 2.75" mid pipe, Lethal Performance over axle pipe kit, hangers/mufflers, and be good to go. Looking at roughly $1300 new.

RIO RED SNAKE said:

Buy 2010 GT500 stock mufflers and just try just that first. They have 0 drone and are extremely driveable daily muffler but when you get on it they sound great. Its probably one of the best mufflers to come from the factory as far as limiting drone while not choking the car too much.

the 2010 GT500 are a direct bolt on, same hangar locations etc. Went from Corsas that made popcorn everywhere i went to those stockers and i couldnt be happier. They sound so clean

Click to expand...

Right now I have 2010 GT500 mufflers adapted with a 3" to 2.5" reducer to pass a decibel test here in Germany. They do sound good with little to no drone and its amazing. I can actually have a conversation or listen to the radio haha

gimmie11s said:

^^ that's a great idea but unfortunately they are only 2.5".

I want to convert mine to 2.75 or 3" from x-pipe back which is why i like the 11-12 gt500's.

Click to expand...

What are the power limits with 2.5" and 2.75" exhaust.

gimmie11s said:

^^ that's a great idea but unfortunately they are only 2.5".

I want to convert mine to 2.75 or 3" from x-pipe back which is why i like the 11-12 gt500's.

Click to expand...

Why dont you run 2.75 from the headers back and then have the exhaust shop blow up the end of the axlebacks to step down from 2.75 to 2.5? They have a machine that goes inside the tube and then it opens the opening perfectly to what size you want and then clamp it. I honestly can't see any power loss or sound being ruined. just my.02

usafimj said:

What are the power limits with 2.5" and 2.75" exhaust.

Click to expand...

Good question. I do remember reading (and now i cannot find the thread) where a TVS GT500 picked up 25+ horsepower going form 2.5" to 3" exhaust.

There's also this:

So here's what I've found so far if anyone wants to convert from 07-10 GT500 2.5" exhaust to 2011+ 2.75" exhaust.

- 2011+ mid pipe & mufflers
- Lethal Performance Gen 2 mandrel bent 2.75" over axle pipes
- 2x Mid pipe to over axle pipe clamps

Where I'm coming up short are the Rear Hangers. Tasca does not provide a part # or show it in the diagram for the GT500. They do show the rear hangers for the 2011 5.0 but not sure if they're the same.

The muffler brackets are the same on 11-14 5.0's as 11-12 gt500's, i know that for sure. it's why the gt500 muffler is such a poplular upgrade for the Coyote guys.

Buy the left and right muffler brackets from tasca and you'll be golden. s197 chassis the same and they should bolt in.