Re: 954 clutch problems?
That's clutch slippage, plain and simple. If you just put the plates in, then yeah, you did it wrong. Practicing wheelies will damage your clutch basket more than anything, shouldn't do TOO much to the plates. You haven't burnt them out yet. Did you use all of the friction plates? If so, I'll bet money you replaced the 2 "different" oem friction plates and the front and back of the stack. The one at the very back (as already said) is a different diameter. The EBC kit just comes with all the discs the same size. That EBC disc is covering and rubbing the judder springs.
Simple fix. Open it all back up and replace the very front and very back friction plates with the OEM plates. The ones in between can remain EBC if you so choose. And yes, the stock plates are about as good as you'll get.