So I currently have a hfc and custom catback along with other mods and am going for a pro tune this week. I need a new catback and my question is will it affect the tune if I change the exhaust after the tune as I don't think I can get it done before hand. Or should I reschedule the tune?

 

Hi, it probably won't change much with a catback change. It would probably change more with a test pipe change though. Either way you should let the tuner know to leave room for that.