I bought an 06 Stage 2 cobalt sc and I believe it has a ZZP catless exhaust. I need a cat to pass inspection so I was gonna have a shop add one on. Will I need a tune after that? Right now there's no codes or anything.

 

For optimal performance yes, but adding a cat will not require a tune unless it's a really poor flowing one.

 

Thanks for the reply, I will probably get a tune eventually once I pass inspection but its good to know that I shouldn't expressly need it.