on my plus 21-5 i run the RMV 3 speed with 1mm springs, carbon shoes & 14T bell, it does get a bit of wear, especially on the interrnal springs (i found a spring manufacturer who makes the same springs for about 20c eash instead of the $s for the RMV ones) and the section of the shoe spring that clips onto the crank shaft does get some wear. but when well maintained this set up rocks for this engine.

for my RB s7ii i use a mugen fly wheel, 1.1 springs & carbon shoes & a 13T bell. this engine needs to rev out a bit more before the clutch engages as it has a lot less bottom end than the plus 21-5. this set up helps me get a bit more punch out of corners & before the jumps on the tighter tracks.