There is only one flaw to any of the traxxas engines, thats the cheap carb, it will crack. But it comes with a simple fix, the OS .18 tm carb fits and works great. My bro runs a 2.5R and does very well with it, finished 2nd friday night, behind a guy running a RB V12.
A basher engine, traxxas, but if your going to race, I would pick up a OS .12tz or RB V12.