Alright you have already tried dropping a nice thousand already so I think the door is open for ya on this. Go with POF, plain and simple choice for the money. If you have it to spend on one, you don't get any better for a piston upper. Someone posted a video of how and why the POF system is better, but I can't find it or I would have reposted it for you. Anyway, do your homework and you will see yourself.