ORIGINAL: iexion
Gearing also helps. If anything thats the first thing you'll want to change out before trying a new engine
Trying to make an LST go fast is going to take more than just regearing it. These things are pigs and it takes a copious amount of power to get them moving fast. A
good engine is a must, swapping out for the tallest clutch and spur combo available, and then using the transmission gears from the Brushless conversion kit to be stupid fast (for an MT) and FOC kit.
This would be the way I'd go if I wanted to build an LST for speed. The Mach .26 will get it moving decent, but if top speed is the objective (and it is) then that engine wont cut the mustard. A very good .28 or .30 will be needed.