i ran a spec stage 2 in my almost stock wrx (~230whp) it held that very easily. people who drove my car that were used to a stock wrx clutch thought it was really stiff/touchy, as did i after first installing it. But once i got used to it, it was a lot easier to manage than the stock clutch. By that i mean that it engaged exactly the same all the time, it didn't even bother me in traffic. I liked it.
I plan to run the M20 flywheel and possibly the spec stage 2 or something very similar to it on my M42.
You're on the other side of the pond right? what compression are you running? i'm thinking of using 9.0:1, same as a wrx

and maybe even a vf34 turbo. sry to go off topic
