You can't put a HP number on the piston failures. There are guys running over 600 hp with no problems, and there are guys cracking them at 500 hp. I had cut LBZs in my rebuild and they ran over 700 hp without a problem, but they were only in for about 4500 miles.
kinda like theres guys over 700hp not bending rods and guys like me under 600 who are bending them