Backpressure
 

Do you get performance gains by lowering back pressure on a 4 cylinder? I am thinking about taking out my cat converter.

What engine do you have?

Dave

Not sure if your state has smog laws but removing the cat is a no-no here in California :nono:! That being said if you do remove your cat for so called performance gains you should have your vehicle tuned (like a Trifecta) for such a mod :wink:! Your vehicle is set for the backpressure / exhaust that is currently on your HHR and just eliminating the cat will make it preform worse :surprised:!

Best-O-Luck :thumb:,

I have a 2.4l and live in a state with no emissions requirements. Thanks for the help. Just trying to save gas money.

You will not gain anything by removing your cat except maybe a check engine light...

There might not be any emmissions testing, but there are emission requirements. There is a heafty fine for removing a cat and not installing a new one.

To echo the others here, please leave the cat alone, all you're doing is asking for issues and added expense. Things are better engineered than they were in the '70s and 80s, back then pulling the cat off did help some vehicles, but you still had to compensate with carb jetting etc. And as solman98 kindly pointed out, you can be fined and when it comes time to trade or sell your vehicle....guess what you need to put back on.

Since youre not running a turbo i say leave the cat in its place.

Go ahead and do it. Then you can spend all your time and money trying to eleminate the check engine lights,not to mention the "reduced engine power " mode. And while you're at it, remove the hood. That's good for another 15 RWHP.