If I went Mamba with my 18MT, I would go with the 5400 because it'd be a bit more controllable. I've seen the 8000's, they're retarded, can't even hit the brakes without the thing doing a forward cartwheel. Plus, the little guys can barely absorb hard landings as it is, maybe I'd up the shock oil to 60wt like a guy at Hobby People did though.