Ok so heres my deal, Last year i installed a new act clutch kit (TY2-HDMM kit but with the 3000605 disc) on my car . I have been progressively turning up my boost and noticed that when i hit about 17 psi that in 4th and 5th gear i begin to have clutch slip. when i am punching it . So i am thinking of upgrading, my question is could i just upgrade the disc and reuse the pressure plate . I have only put about 4000 miles on the current setup and have not let the clutch slip maybe 4 times. or am i going to have to replace it all.
Sean

You can't tell the condition of the PP [and flywheel] until you tear it apart and look at it.

If you've got hot spots, they're junk and you need to replace everything.

If not, and they're not scored and are flat [should be with that few miles on them] they normally are reusable.

However, while the disc is what "grabs", the PP is what provides the pressure...
So even if you get a grabbier disc, there's a decent chance you're going to have slippage again unless you replace the PP.

Just for the record, I don't have any specific experience with ACT stuff, so there's always the possibility that the specific disc you have is more prone to slippage, and a better one will work fine with the PP, you might want to run it by ACT just in case.