Exhaust Leak - 91 GT

[banditmwp]

I have a 91 GT Convertible that has an exhaust leak i can't quite find. It seems to be coming from the passenger side header area. I have Mac unequals on the car, and a Mac off road h-pipe. The leak is a tick that makes the car sound like a damn lawnmower from 1500-3500 RPM. It is QUITE embarassing. It is worse when the car heats up, which strikes me as odd. I can't feel air anywhere around the header flanges or the header/h-pipe flange. I put a new copper header gasket on a few months ago, but the noise never stopped. The flange is tight where the header and h-pipe join. HELP!!
:damnit:

 

[5 Liter Mustang]

i had some leak problems with a small crossover pipe, (not the H-pipe) on the stock H-pipe assembly. There's a 10mm nut that i had to tighten. Also, its not uncommon to find a small rust hole in the H-pipe

 

[banditmwp]

thanks. I'm going to go to work tomorrow (although we're closed) and put it on a lift and i will be sure to look the h-pipe over closely.