I'm adding a Cobb Catback... moving from the stock catback. My 2005 STi has been protuned by SS with a Titek catted Downpipe, and I just wanted to check... do I need to avoid spirited driving until I can get a re-tune with the new catback... or no big deal? Pardon my ignorance... just thought I'd ask.
A tune is not required from a safety standpoint when installing a cat back exhaust. Turbo cars, like your STi are much more sensitive to modifications and typically require retunes. Scott Siegel works here at Forged now.