How do I tune out the ole LT1 slow down backfire.. The way my car was setup my exhaust is waaay to big for my motor (2" headers, 2x3.5" straight pipes dumping out of flowmasters..) It's left over from my old blower setup.. Basically whenever I take my foot off the gas to slow down, the car rumbles, and backfires.. How can I tune that out?

 

Without cats, its fairly normal to get a rumble/popping on coast down. Check the tables that control the point at which the PCM shuts off the fuel on coast down.

 

Great, thanks but what exactly am I looking to change in those tables?