The Mugen MT .12 or the MR .12 (the MT .12 bighead is hard to find now). Bottom line, for .12's these babies are awesome! I have one in my TC3 and its a bat out of hell. High RPM, cool temps and enough HP to go around. I have yet to find an MT .12 or MR .12 owner that wasn't extremely happy with it.
I'm having a hard time killing my OS .15 CVR though so it may take me a while to have to replace it hehehe