When I first installed these I had a leak on the passenger side header. When I puller the header I found that the gasket didn't cover part of the header flange. In reality the problem was more with the header than the gasket but the gasket is also somewhat at fault. The reason I say this is because the gasket port size is a good bit larger than the port on the head. If they offered different gaskets for different part sizes you could likely get a better fit. I.E. one gasket for stock ports, one for larger ports, etc. Much as they do for Ford and Chevy. In the end though I cut the gasket into separate pieces for each port section. I then elongated the holes for the offending port and got it to match the header flange. No more leaks and is holding up well at 3500 miles.B