adding headers, does NOT require a tune.
you are just unlocking more by adding headers, so that way a tune can be used better.
I'm probably gonna get laughed at but I'm gonna have to ask this.
I want to install headers in my car but NJ has those California low emission laws too. If I got headers install would my car fail emissions (I'm going to keep the catalytic converter) even if it doesn't throw out any codes?
Speed daddy's don'tIf the inspector is anal enough and there's no sticker that says it's emission compliant then chances are you will fail. Then again most inspectors aren't that anal and will just check for a cat.
TOGS include a sticker with there headers. No sure about the cheap ones like Speed daddy etc.
there is a good chance that even with an aftermarket cat an 01+ vehicle may get stuck in a diagnostic loop of sorts if it does not see an adequate response when it runs a self check on the cat. if you have no cat the car will be stuck pig rich and even if you have some aftermarket cats because they are less efficient it may cause the same condition.
a 3" high flow cat is most likely going to set a P0420 code.