I have both. If you have a carb off of an os tz the crf is a great engine. I put a carb off a 18 tz on mine and it tunes easy and it is fast . It may not be legal if you get checked but the .12 tz carb would work too. The red dot is fast also but the carb likes to be rich on the bottom . I would say either one will win races if the car and driver are up to it.