Cant find a definate answer on this. Does a turbo back exhaust with sports cat on my 2010 S3 need mapped before it will run good, or is it just best to get it mapped to make most of gains and to put light out? Any input appreciated, thanks!
It would run fine I had my powervalve on for about a month before getting it mapped and never had a light come up. Ran as normal too. You may find certain exhausts throw up lights more than others though.