I'm with grizz1 on this one..I'm now running 2 alloys with 1.1 springs and 1 carbon with a 1.0 spring in my 7 port,3 port and MG66 only difference is the MG66 will pull the higher 14/46 gearing while the others prefer the standard 13/46 setup..and I use k-factory hardened clutch bells and have never seen a groove inside one unless you let your shoes wear down so the springs engage with the bell..and if you do that you have no one to blame but yourself..k-factory sell under the name racers edge in the USA.