I recently have been getting a back fire either while shifting from 2 to 3 or, also from 3 to 4 but its just one small pop nothing like a gun shot. And also if im going down hill to where i can take my foot of the gas and still maintain a speed of 35 while in 5th is has a deep gurgle. I have straight headers (heated wrapped) to glass back exhaust so i dont know if its my exhaust casusing this or how could i find out if im running to rich?