I had the same exact problem with some $1200 billet fuel injector tips for my truck, supposed to be indestructible and lifetime guaranteed. Guess what, after the aplication of a little boost and heat i blew a nozzle apart. The answer i got from manufactur was that i ran them with too high of EGT. Funny, the aluminum piston it sits above didnt melt. After some calls and discussions about going public i did finally get some new injectors, but i wont run them again. Guess i could sell them, but thats not the point, if somebody says 100% guaranteed, they should without question fix it if they break, not weazel out of it or even try to.