i am driving home from work and i pass through the movie theater and when leaving i bang 2nd and 3rd and approx 1 min later the exhaust sound like when u have ur foot on the gas pedal very lightly and u here the backpressure going pop,pop,pop ect. and there is a noticible amount of power loss anyone that can help please reply. its a gsr with jdm 4-1 header to a carsound cat and ni exhaust but in between the header and the cat there is a donut the s2000 donut and i recently tightened the bolts around that but i dont think its that

 

First thing I would check is for exhaust leaks. Then I would check to make sure that your timing belt did not jump.

BTW when you say noticible loss of power. How noticeable is it slightly or a Very noticeable Loss.

 

very noticible but the exhaust header and cat are like 3 months old and i have had to replace the bolts on the cat to header flange they blew off i am guessing that maybe the bolts lossened and the flange is sitting cocked and i am getting too much backpressure would that make sense ?