Man, i'm going through the same shit you are, except I just use a 4 puck ceramic disk, and stock pressure plate/flywheel. It will slip sometimes at 13 psi, esp on a hard WOT 2-3 shift. I've heard nothing but good things about the Spec clutches holding power, so I would check this out: pull off that rubber dust boost on the release fork, and get a good, bright light and try and peek into the bellhousing. Look right around the TOB and input shaft, and see if you can find any trace of dampness, or oil anywhere. It should be completely dry everywhere. I had one clutch destroyed by a leaking trans input shaft bearing seal, but I did the light trick, and saw the fluid on the input shaft and the pressure plate fingers..wasn't too hard to figure that out..I do know of others on here who have the spec 3, running over 20 psi without any issues..so thats all i can figure out i guess :shrug