I asked that same question earlier this month. Bobby, bsshogs, said that he uses them and hasn't had any problems. I'm expecting a couple in the mail any day soon from the friend that asked me about them. From what I was told, he couldn't see any difference between what PSI sells and what he got in his order.
Just finished making a few of these kits and they came out very nice. Put them beside a PSI kit and you can't tell any difference. I did the Chrome Comfort pen kits and used the PSI instructions and bushings and experienced zero problems. At the price I paid and free shipping from Amazon I can't see where you could go wrong. I'll try more of the kits in the future. Left a message on their customer service number and within about 15 minutes I got a call back with an answer to my question. Very impressive!!!