RE: Serpent S811 Cobra-T or the Mugen MBX6T M-Spec
mugen all the way... driven serpent and worked on setup for a friend, we would get it working one day then go to a different track, and start over. also, it was loose or it pushed. and didnt work well in rough. he ended up selling it and went back to mugen.
mugen has more traction then any truggy, ive been loosening up alot (far off mspec setup) and it turns like a buggy but more stable. just buy extra front arms or boil them ... ive never broken an arm but others have. my dad is a sportsman driver and crashed alot, we boiled his arms and he never broke one and had some hard hits. i run pro and havent broken one either. ... also, when you get the truggy, check the shimming on the ring and pinion gears, they should be a little bit notchy (NO play at all) and let them break in.
hope this helps.