had the nismo exhaust on for a bit. ive tried to fix it multiple times. not sure what it is.

everytime i hit the throttle. you can hear a little

SSSSSSSSSSSSSSSSSSSSSS sound. like something is rattling. or something isnt tight but checked everything.

 

THere is a little black box/cage right behind the exhaust can, make
sure that the hangers arent hitting that. I had that issue with my
Magnaflow.

 

not that.

 

if you think you have an air leak, wrap aluminum foil tightly around any place pipes meet up. start engine, rev it, see if the foil has gotten a hole in it or come off in a spot. If that doesn't do it, you can restrict some of the airflow comming out the tail pipe to raise pressure and hopefully force air out the foil.

 

Do you change out your cats? When I had my nismo exhaust it always rattled with my kinetix hfc.