i have been fighting exhaust leaks for ever and finally fixed 95% of them but I think I still have one left but I cant hear it unless im driving next to a wall or a car but its not a huge leak I have already smoked it with sea foam and don't see any real leaks and im wondering if the flex pipe that came in the pace setter kit leak very commonly because I don't see any leaks but I can also hear it at cold start so any suggestions? could it be the flex pipe?