IMO< most def. the RG21,w/ Jammin jp1 pipe, this motor will last you FOREVER, it is perfect for sportsman class racing, hold's a tune period. if you get good enough not to crash, you will see that you dont need all that power, most of the time you cant get the big powerful motors to hook up till the straight aways,my 11 yr. old son runs xray xb8 tq, os rg 21 jp1, in sportsman class , rarely crashes, and finishes top 3 every race.[sm=punching.gif]