Depends where you live. The resonator does nothing but lower noise levels. It won't effect emissions. If you have volume laws then I wouldn't recommend removing it because you will be pretty damn loud. Cats are illegal to remove unless they malfunction, but high flow cats are legal so long as your car still doesn't put out more than the legal limit of whatever... (unburned gas and flourocarbons or whatever). Check your state laws on resonators. Cats are federal offenses though, just so you know.

...Glad I don't live in Cali.

 

I'm not sure where to find the law on whether or not resonator is legal in wisconsin. I ran a search, and none of the result came up what I was lookin for can someone tell me where to search or someone here from WI wanna tell me about the law?

 

That I dunno. You have no idea how long it took me just to find License plate laws in NJ.

 

When I lived in Arkansas, there was no emission testing. It was great. Then I moved to Maryland, now I can't have as much fun anymore.

 

A good resource is the SEMA site http://www.enjoythedrive.com/ They have a section about "your car and the law"