No problems
I have Campion GN-1's on my stock block and have seen as much as 44lb of boost (spikes) on them and no cracking problems at all. I run consistantly 28 plus lbs of boost on them.. Many of the cracking issues are more likely tunning issues than faulty heads. You can destroy anything if you detonate it hard enough.. Buy them run them if you know how to tune you'll probably never hurt them.. Just my thoughts.. Dave