I tried getting someone to cover the end of it with a rag and I felt around the system but could not find anything. You can't hear the leak at idle or if you rev it up. You have to drive it in order to hear it, but it only seems to leak if you give it half throttle.. But then again it's hard to hear over the exhaust and intake at WOT.... I took it to an exhaust shop and they did the same thing I did. I told him he needs to drive it to hear it, but wouldn't drive or or ride with me in the car.

I just replaced the catback a couple of days ago. I heard the leak before that but thought it was from the resonator on the old exhaust leaking from my shitty welds, but after putting the new exhaust on it still does it. My header and midpipe are fairly new with new gaskets.

If it's not a leak what else could sound like what I'm describing?