Hey guys I've got a question. My 06 gt sounds like it backfires a little on the freeway when I'm doing like 75 and punch it the rpm's shoot up and it down shifts like its suppose to but then it sounds like a real short backfire. Any ideas?
Mods k&n cold air intake, muffler delete. No tune.

 

mine was a little odd 2 weeks ago, any time from light load the gas was pushed very hard it would ping just for a instant when the pedal was first hit. next fill up it went away. they just switched away from the summer blend sep 15th in ohio, guessing maybe the thing needed to adjust to the combination of winter grade fuel and lower air temps...not sure how much 'learning' these things do.

 

It's normal I have a muffle delete as well and my car does the same thing when I floor it, Its even louder on cold days It sounds awesome IMO.