my other tmaxx has the 2.5r in it. it is rippin sob. the 2.5r would be a good upgrade for it. mine has the extended chassie on it and it will still do wheelies when it hooks up. the 2.5 is a good motor to before i put the 2.5r in it. it had the 2,5 in it it still ran pretty good for even haveing a broke piston in it. u can get the eztart motor on ebay for about 20 bucks or less with. if you buy the motor of there too you will be at about 120 for ezstart and motor then you will have to get exhaust and that will depend on what kind you want for the price. you could do the 2.5r engine, ezstart , and compltete exhaust for right around 150 off ebay