Most Restriction, stock cats or mufflers?

[dark snake]

On our GT500's, which item has more exhaust flow restriction, stock cats or mufflers??

My '08 is Dyno Jet dynoed at 600 rwhp, 625 rwtorque, w/16.5# boost @ 700 engine hp. I have the new MRT H-pipe w/reduced cats with Corsa Sport Mufflers (straight thru). But, it's way too loud for normal use, crusing, and staying un-noticed by the authorities. Option 1: Stay with MRT H-pipe & stock mufflers (which is much quieter). Option 2: Stock H-pipe/cats with Corsa's (which is louder then option 1 & sounds great).

Not sure which set up is best for hp gains & engine w/16.5# boost, but knowing which item has the most flow restriction will help.

PS: If I stay with MRT H-pipe w/reduced cats, which baffled performance muffler is a good option, being quieter then straight thru Corsa's?

 

[Blazeone]

I think it's a safe bet that the cats are more restrictive.

 

[bull3441]

Justin of VMP made over 700whp with the stock cat-back. The '08 mufflers are ugly and on the quiet side, but they are fine at your power level. Keep the MRT and just put resonators on the car. I have LT's, o/r x and the Corsa sports. the combo was Nascar loud, till I put the resonators on. Now I can actually talk to the passenger while cruising. MBRP has nice resonators for $74 each, 304 SS. This is what I have http://www.amazon.com/R1012-Outlet-Overall-Stainless-Resonator/dp/B000OB175M

 

[2011 gtcs]

I would just run a ofr x- pipe and stock mufflers.

 

[tbazzi21]

Justin of VMP made over 700whp with the stock cat-back. The '08 mufflers are ugly and on the quiet side, but they are fine at your power level. Keep the MRT and just put resonators on the car. I have LT's, o/r x and the Corsa sports. the combo was Nascar loud, till I put the resonators on. Now I can actually talk to the passenger while cruising. MBRP has nice resonators for $74 each, 304 SS. This is what I have Amazon.com: MBRP R1012 2.5" Inlet/Outlet 16" Body 20" Overall Length T304 Stainless Steel Resonator: Automotive

Do you have an exhaust clip of your setup I would love to hear it

 

[kent1]

I would just run a ofr x- pipe and stock mufflers.

+1

I run lethals high flow cats and SVT1's. It is fairly quiet but louder than stock! It has a very nice rumble and sounds good at idle. There is no drone when cruising. Keeps you out of trouble with LAW.

 

[bull3441]

Do you have an exhaust clip of your setup I would love to hear it

Not since I added the resonators.

 

[sedanman]

I like the stock cb with a o/r X, but if I decide to go louder I will swap to a flowmaster cb.

 

[dark snake]

MRT Hi-Flow mid pipe & stock mufflers

Thanks for the quick replys, great info! I'm sticking with MRT Hi-Flow h-pipe & stock mufflers. Sounds good @ louder & lower tone then stock, nice idle rumble, & at mid-range & WOT I can hear supercharger whine, CAI sucking air, & my music again! :beer:
If I get bored with the quietness and decide to go a little louder with SVT1's or Flowmasters, which Flowmasters would you suggest? I see Shelby Parts offers 3 models for our cars...American Thunder @ Alum./Steel Moderate (most expensive?), Stainless Steel Moderate, & SS Aggressive.

 

[1 Alibi 2]

Running Kooks 1 3/4" longtubes with catted X pipe through " stock " mufflers on my 2011. The cats are smaller than the stock units.
Slightly louder than stock when cruising, & if you want noise, put your foot down. After market mufflers might give you a couple of extra hp, but I don't need the added noise..
.
.

 

[UnleashedBeast]

The GT500 condor engine eats cats when cat over temp protection is disabled by your tuner. If you want an aggressive tune, you don't want it enabled. If you live in a state that doesn't have visual or emission sniffer tests, I'd lose the cats.