it depends what kind of batteries you're using. The controller i use for my rc10gt, and i had been using it in my t3, but the receiver died in the gt, so the radio system was donated to it. so after letting the t3 sit for a while, and after having a great time with my max and 25 system, i figured i'd get a sidewinder system for the t3 to bring it back to life. previous to that i was running a reedy modified 19t motor w/ an lrp AI, and its faster then that now. Until i can get the updated castle link software (having download issues), i haven't bothered to reprogram the esc with radio so i've just been running my 3s lipo, and it books. its geared tall (87/12) and with the lower kv motor (4600) it probably runs a good 45mph, give or take. but again the truck is geared pretty tall so there's more speed potential. And where the batteries come into play is the motors are rated at rpm/volt. so the more voltage you run through the motor the more rpm it will turn. but depending on how its geared i don't think you would have a difficult time getting 40mph out of a 2s lipo.

my max system is 87/15 (5700 motor) and with the 3s lipo its gotta be hitting 50+. i mean its just ridiculously fast. most of the time the tires spin when it launches on the pavement, but when its mid throttle and accelerated, the front end comes right off the ground. i mean its seriously just impractically fast.

ideally with a 2s lipo i think you'd be really happy, but since its a budget, and if you're running nimhs i think you'll still be pleased. Nimhs are heavier and will have less of a discharge rate so there won't be as much "punch" to it. You'll also definately want to get deans or traxxas high current connectors. if you're running tamiya style, they're fine for a crawler but just useless in a brushless system, there's just too much resistance.