"Take a look at the counter rotating double motor setups:"
That was a bad, bad thing you just did lol.
ZP, yeah you would want to buy some hardened 8mm with the 6mm bore already there, not sure either where you'd find... but I'm sure it's available.
Another thing for the fifthers here (fitherz?) Ryu, aqwut and others, hows about an outrunner trannyless? I think what's nitro posted this some time ago-
http://hobbyking.com/hobbycity/store...me=Turnigy_80-
7000 watts oughtta do pretty good, there's a 130kv and a 180kv.... for $150!
You know someones gotta do it