mattyb,
I assume you want to get power to the ground by not spinning the whells right. Keep in mind if you have the stock diffs in your matrix lighter oil is better. those diffs really like the light fluids. I am running 3k in front and rear and 5k in the center. I hook up on most surfaces except dry hardpacked clay, I think I would have to get new tires for those tracks. also what tires and compounds yuou running. prolines m2 compound really works well on tracks.