Exhaust question - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

km9v · 10-27-2011, 04:24 PM

This may sound like a dumb question, but the stock SS exhaust is 2.5" in diameter right? Can a 3" cat back bolt up to the stock cats or would I need 2.5"?

JDP Tech · 10-27-2011, 04:50 PM

If the cat-back is made specifically for a 2010-2011 Camaro SS, then yes, a 3" cat-back will bolt right up (unless it states otherwise). They usually clamp onto the stock exhaust as a 2.5", and immediately go up to a 3".
What system are you looking to get?

RichGreene · 10-27-2011, 04:52 PM

If its a killer deal you can have your local muffler shop weld in reducers otherwise buy the 2 1/2".

Cpanthers85 · 10-27-2011, 05:00 PM

I am going to tag on to this.. what if you get a set of headers with connection pipes that say "For stock exhaust or 2.5' aftermarket". I have the American Thunder, which is 3'', but it's currently bolted up to my 2.5'' stock cats...will those 3x2.5' connection pipes work?! (looking at Kooks Step Headers) I'd assume so...

Juiced1 · 10-27-2011, 05:09 PM

Most 3" systems neck down to 2.5" at the connection to fit the factory system without welding. Headers and catbacks will both do this unless you get something custom. A way to get around it is to have a exhaust shop cut out the necked down 2.5" tubing and weld in a 3" pipe to replace it. Or you can get a complete Stainless Works performance connection system.

km9v · 10-28-2011, 08:46 AM

Thanks, I wasn't sure if a bought a 3" cat back that it would neck down to 2.5" & bolt up to the stock cats. I was thinking of getting the Doug Thorley cat back but it appears to be 2.5". It's a great sounding system but if I'm replacing all that pipe, I'd rather it be 3". I may just get an axle back system. I'm still undecided.

10-27-2011, 04:24 PM	#1
km9v Drives: 2011 Camaro SS/RS M6 Join Date: Oct 2010 Location: Beaumont, TX Posts: 419	Exhaust question This may sound like a dumb question, but the stock SS exhaust is 2.5" in diameter right? Can a 3" cat back bolt up to the stock cats or would I need 2.5"?

10-27-2011, 05:00 PM	#4
Cpanthers85 Drives: 2011 Camaro 2SS RS Join Date: Jul 2011 Location: Pittsburgh, PA Posts: 470 View My Garage	I am going to tag on to this.. what if you get a set of headers with connection pipes that say "For stock exhaust or 2.5' aftermarket". I have the American Thunder, which is 3'', but it's currently bolted up to my 2.5'' stock cats...will those 3x2.5' connection pipes work?! (looking at Kooks Step Headers) I'd assume so... __________________ 2011 2SS/RS L99 2017 Chevy SS 1979 Z28 Mods: Kooks Long Tube Headers, RotoFaB EForce CAI, American Thunder Catback Exhaust, PFADT Stage 1 Drag Kit + Front Sway Bar, GM Strut Tower Bar. ZL1 Fuel Pump. Nitto NT05R. RX Catch Can.LS9 Cam and Springs.LS3 Conversion.JRE Fuel Rail Upgrade.Edelbrock Eforce.60# Eforce Injectors.Extreme Racing Tune. 523/495 MY BUILD THREAD

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10-27-2011, 04:50 PM	#2
JDP Tech Drives: 2010 CGM Camaro 2SS/RS 429 LSX/F1X Join Date: Aug 2011 Location: Sandy, UT Posts: 429	If the cat-back is made specifically for a 2010-2011 Camaro SS, then yes, a 3" cat-back will bolt right up (unless it states otherwise). They usually clamp onto the stock exhaust as a 2.5", and immediately go up to a 3". What system are you looking to get?

10-27-2011, 04:52 PM	#3
RichGreene Account Suspended Drives: 2011 1SS M6 Green 1993 Custom Eldo Join Date: Jul 2011 Location: Ohio Posts: 973	If its a killer deal you can have your local muffler shop weld in reducers otherwise buy the 2 1/2".

10-27-2011, 05:09 PM	#5
Juiced1 Account Suspended Drives: 2012 2SS CAMARO 45th Join Date: Apr 2011 Location: St. Charles, IL Posts: 18,663	Most 3" systems neck down to 2.5" at the connection to fit the factory system without welding. Headers and catbacks will both do this unless you get something custom. A way to get around it is to have a exhaust shop cut out the necked down 2.5" tubing and weld in a 3" pipe to replace it. Or you can get a complete Stainless Works performance connection system.

10-28-2011, 08:46 AM	#6
km9v Drives: 2011 Camaro SS/RS M6 Join Date: Oct 2010 Location: Beaumont, TX Posts: 419	Thanks, I wasn't sure if a bought a 3" cat back that it would neck down to 2.5" & bolt up to the stock cats. I was thinking of getting the Doug Thorley cat back but it appears to be 2.5". It's a great sounding system but if I'm replacing all that pipe, I'd rather it be 3". I may just get an axle back system. I'm still undecided.