Okay, I just installed my Mac X on my '04 with 2,500 miles on it. I used the gasket that came with the X pipe, not the factory one. I thought I read somewhere that the addition of an O/R pipe allows you to hear the valvetrain a little more. Anyways, in 5th gear, under like 1,500, I can hear what sounds like a very, very slight leak. It may just be me, or may be the valvetrain. But it doesn't pop at all under decelaration which is a common occurence with exhaust leaks. So, my question is this, is there a chance of a leak with the Mac gasket or is this in my head? If so, should I get another factory one or reuse my old one with the 2,500 miles on it? Or is there another way to make sure it is a leak? Help, I am soooo confused.