RE: TNX 5.2R, REVO 3.3 OR MGT 4.60
I don't know much about MGT's but I haven't had one beat me racing yet.
But Revos are a good racer, and the 3.3's are fast. Probably not as fast as the 5.2 but on the track it would be easier to handle and probably easier to race. The Revo's I've tried have a floaty-er feeling to them. They soak up bumps really well. The TNX on the track (I'm talkin 3.0 TNX) on the other hand seems more raw and direct. THey're no slouch either.
Go with what the LHS has