You're going to get different opinions on what will wear out first, I went with the 904 kit from bonnevilleperformance.com and I'm very happy with it. I can't see any option wearing out before 50-60 thousand miles at a bare minimum. I went from 54rwhp to 70rwhp and torque went from low 40s to a steady mid 50s throughout the rpm range.

Always remember to be yourself. Unless you suck. Then pretend to be someone else.