on i hvae a booster and here is what i have learned...

on regular speed (non boost) the sh!t is slow as hell! i have a 3.8 motor and it runs like a..uh.. i donno but really slow... 2.2?

on booster mode itll rip! the thing is crazy fast.. faster then regular 3.8 motor...

so in conclusion.. always keep it on for speed, but take it off for turns so you wont flip.. =P