RE: mamba is good...no?
There is absolutly no possible way to get the 9000 on a offroad track. You'd have to go with a 1cell lipo! Even the 7700 and 6900 were worthless nukem monsters. Your better off going with a 4600 and running 3 cell and some gear. Then it'll still be fairly practical for off road.
Even for drag racing the 7700 and 9000 are too hard to tame into something useable. The only purpose those winds serve is to relieve a newb from his money twice. (the second time is when he wisens up and gets a 4600.)
I'd look towards the MMpro, I belive it has dynamic timing, and just go with one of the hotter winds that Hpi recommends for that truck. A MM pro and a Trinity Duo 7.5 or 6.5 would be plenty in a firestorm.