I put lots of miles and lots of passes on some kb243s before one of the cracked all the way across the top down to the pin. They had been ridden hard though, I used to hold a grudge about it but they got abused day in and day out.

I currently run some kb107s in my 360. When the air is good it makes close to 500hp. It's been on 3 drag weeks as well. I paid $245 for the pistons and rings from summit! kind of hard to complain.