when i lay on the throttle and let off right away sounds like a bird chirp goes throught the exhaust . it still has the stock pipe on it only mod is a dynojet kit what could be making that noise or is it normal could it be some sort of back fire

 

Could be a baffle loose, broken or cracked inside the muffler. I had a baffle let go a couple years ago, finally got around to fixing it this year. What ever let go in mine came out in about a dozen 1" peices when I cut the end off the muffler to look.

 

turbo? hahaha