I'm sorry to hear that you had a bad experience with them. They told me if my car knocks at all, to write down at what rpm and what gear and they will take care of it. So far it only knocked twice when I was WOT in 2nd, but I also went a bit past 7000 rpms.

Other than that one time, everything has been running perfectly with no more knocking.

*edit*
Well tonight I was messing around with my friend in his evo and I peak boosted at 20 psi. I'm pretty damn sure that this isn't a safe amount of boost to run on a stage 2 wrx. I'm going to call CFT in the morning and have them fix this shit before I blow my motor.