i recently installed a high flow cat. I cut the flange on the downpipe and then clamped the cat on. A few days later i noticed a leak, so i put it on a lift running and found the clamp joint leaking. I welded it up and took it for a drive, but still heard it leaking when driving by objects. So again, i put it on a lift with it running and it sounded quiet, i put my hand around everything,(all joints, donut gaskits) and did not feel a leak. I then had my boss rev it up while it was in the air and could not feel it but could definatly hear it. I

I was wondering if you could hear either a donut gaskit or a manifold gaskit leak without feeling it and what is the more common to leak. its been driving me nuts, and is just plain annoying. Since i use this is my only car and i use it daily, i don't have much down time, atleast when the exhaust is cool.

You should be able to feel any leaks. You actually don't have a donut. You have a flat manifold to DP gasket.

Did you remove the down pipe? Sounds like something that opens when the engine moves.

i didn't remove the dp, but it did get jared around a little, maybe i'll start with that gaskit because it will leave me with the least down time. It sucks haveing a nice sounding exhaust with the raspy leak sound when you go by something, or step on it