To change exhaust for TT setup or not..

[Levischilz]

I currently have stock exhaust except muffler delete. Does anyone know what may change after I get the twin turbo setup in place?

Im using the AGP TT kit. I know that the car to me with the muffler delete is not loud (ls3).

I know our cat's muffle quite a bit. I also know that turbo's will muffle the exhaust.
A. How do you think the exhaust will be in terms of volume compare to now? The cats are going away with the turbo install.

B. Is it worth the money to change to a 3" system now while doing the turbo system install. I know it may help relieve pressure on the exhaust side of the turbo. I dont care about the couple hp but more turbo spool time etc vs the factory 2.5 system.


Any feedback would be great. I dont want to spend the money this second since I just ordered the kit but at the same time debating if its better to do it before I get it tuned.

Thanks Levi

[Unreal]

Should be quieter than before, or at least I would think so.

3" exhaust will be worth it.

[Levischilz]

do you think it would need to be retuned if i changed from 2.5 to 3" if I waited?

[BullF-16]

Originally Posted by Levischilz

do you think it would need to be retuned if i changed from 2.5 to 3" if I waited?

Yes, any change in air flow needs a tune. If you want the car optimized.

[2SS45th]

3" exhaust won't help spool up very much, you won't have enough exhaust flow for it to make a difference, unless you are going to make a lot of power.

[caper]

I think he means 3" post turbo..that would help no?

[Levischilz]

Ya right now just looking at 650ish rwhp

[Unreal]

3" will help, not night and day but it will spool quicker.

Yes retune it. Boost will come on faster and you will be moving more air.

[HarryNW]

Glad to see this post here - I am imminent on the AGP install on my (mostly) stock 2013 2SS/RS LS3 and will be meeting with the speed shop team this Friday to discuss the install.

I had been wondering if the AGP TT implied any specific implications for exhaust.

I am leaning towards the Tri-Y Headers from Pfadt for low-mid-range torque gains (DD and circuit car, not a 1/4 mile build) and was still heavily debating the (cat-back) exhaust. If it matters, I have the Dual-Mode Performance Exhaust.

Anything specific to the AGP TT build that would go into the header/exhaust decision? Performance? Fit (as in not interfering with the TT Kit)?

[blake-b]

Originally Posted by HarryNW

Glad to see this post here - I am imminent on the AGP install on my (mostly) stock 2013 2SS/RS LS3 and will be meeting with the speed shop team this Friday to discuss the install.

I had been wondering if the AGP TT implied any specific implications for exhaust.

I am leaning towards the Tri-Y Headers from Pfadt for low-mid-range torque gains (DD and circuit car, not a 1/4 mile build) and was still heavily debating the (cat-back) exhaust. If it matters, I have the Dual-Mode Performance Exhaust.

Anything specific to the AGP TT build that would go into the header/exhaust decision? Performance? Fit (as in not interfering with the TT Kit)?

You can't use the Pfadt headers with a turbo kit unless you are using rear mount turbos. You will reuse your stock manifolds with the turbos. The turbos will give you plenty of low and mid range power.

I do not know if you will be able to use your dual mode exhaust with the turbo kit. I don't see why not but I have no experience with it.

[HarryNW]

Glad I brought it up now then - will not be a factor in the meeting this week, thanks for the quick reply.

With the stock headers then, why does it not make the 2.5" vs 3" conversation mute? If the output from the manifold is stock, and the cat is eliminated, why would a larger exhaust be beneficial? Like the original OP, I will be tuning for an identical 650 RWHP target.

[blake-b]

It is a pressure issue. The larger exhaust will have less back pressure. As Unreal said, you will spool slightly quicker. If I were you, save some money and go with your stock exhaust. It won't make any difference at the 650rwhp level. If, down the road, you decide to pour the coals to it, invest in larger exhaust. Right now, save your money for fuel, tires, and a clutch.

[CyberPredator]

IPS tested taking the exhaust off and gained 50 or so whp in the 600 range. I would say exhaust would make power but upping the boost would be cheaper.

[HarryNW]

Sage advice, and thanks again.

BTW - anyone reading this thread should also read the Article on Exhaust Science provided in this thread. I think the most relevant quote on exhaust/muffler selection , as mentioned by others is:

Knowing that 2.2 cfm per open-pipe hp means zero loss from backpressure allows us to determine how much muffler flow your engine needs. Just make a reasonable estimate of its open exhaust power potential and multiply by 2.2. For instance, a V-8 making 500 horsepower on open exhaust will require 500 x 2.2 = 1100 cfm. Two 550-cfm mufflers will get the job done and contain the backpressure-induced power loss to 5 horsepower or less. With mufflers rated in cfm, see how easy making an appropriate choice gets?