I recently put a put a full exhaust on my 91 teg ls and I am having problems passing emissions.

The exhaust that i put on is a megan racing head w/high flow cat and a cat back. I am in New Jersey and of the 3 tests that they check here i can only pass the HC test. The other 2 test are NO and CO gas which is whats failing. The NO standard here is 1088 and I am putting out 2355.The standard for CO is 0.79 and I am putting out 1.21.

My question is what do I do to rectify this so that I pass my emissions test. I do have a factory replacement cat. If that is the reason that I failing my emissions, I only have one problem with that and that is either the down pipe from the head is to short or the mid pipe of the cat-back is too short when using the factory replacement cat. But with the hi-flow the exhaust is just long enough.

 

It's probably your cat. Alot of those hi-flo cats don't work well enough to keep emmisions ok. Put the stock stuff back on and see if it passes.

 

yeah put on the stock cat, that should help, also remember to make sure your car is fully warmed up when you go.