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Catback exhaust 2.25" w/ 2.5" DP and cat

Old 09-20-2018, 06:48 PM
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Catback exhaust 2.25" w/ 2.5" DP and cat

I really want to get a header for my Cobalt. The problem is, long ago in 2013 I decided to go with a 2.25" catback.

ZZP Performance has a midlength header that looks perfect for what I want... but...
The DP included is 2.5", with no option to go 2.25".

I chose 2.25" because it is a 2.2 liter 4 cylinder engine.
The hp doesn't warrant a 2.5" exhaust, and I worried about not enough back pressure damaging the engine.

If I get this 2.5" DP and cat, is this going to make the car drive bad?

Going from a larger pipe to smaller is the opposite of optimal.
Plus, the question of back pressure and the obvious problem of mismatching.

Opinions please?

Thank you!
Mike85220 is offline  
Old 09-21-2018, 07:09 PM
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No it will be fine. I had the same setup
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Old 09-26-2018, 08:00 AM
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On a non-boosted 2.2 you most likely won't see a performance gain with an aftermarket header anyway so keep in mind this mod will be mostly for looks/sound. You may even lose some low end torque. That said, the reduction from your header downpipe to the back side of your exhaust is probably insignificant and I wouldn't be concerned about it.

Also, engines benefiting from back pressure is a myth. Engines do not need back pressure and back pressure is not good for engines. This myth is a misconception of power losses associated with larger pipes because of the reduction in exhaust gas velocity, compared to smaller pipes, which can reduce the effects of scavenging. Short summery here
jdbaugh1 is offline  
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