Wierd exhaust noise?
 

Well since i've gotten my custom turbo back exhaust, my car continues to make this wierd fluttering/farting/rattling/clicking noise when i let off the gas. The system is turboback with 2.5" piping, a glasspack, and a rear magnaflow muffler with dual tips. It only makes this strange noise when i let off the gas after punching it. the exhaust gets somewhat louder after i let off the gas when it makes this higher pitched strange noise. I'm pretty sure I dont have any exhaust leaks but am not %100 positive. this noise has been the same for more than a year and has not gotten louder.

Anyone have any ideas of what this could be?

Rattle? Could possibly be wastegate. Do search on wastegate rod and compare what you hear to some
 

descriptions.