I don't know which vehicle you are talking about, but my GST had the same problem (Torn gasket). I actually decided to try something differant. I went and got a Savage X Gasket. There's are a lot thicker and take a helluva more abuse. Its works great! You get two of them for like $3 so you will have an extra one. Getting it on was kind of a biatch, but now I don't throw fuel out the back and the gasket is way more thicker and tough then the GST ones.

P.S. A trick I used to get it on was a LITTLE, and I stress a LITTLE WD40. Put some WD40 on the inside of the gasket, not the outside. Slide the gasket half way onto the engine, then slide the pipe manifold over the gasket and it will finish sliding in. Put on the spring and you have a nice tight seal-