The OS RG for pure price is a good motor holds a tune and great low end good for small tracks. I just bought a sportswerks 21 same as SH 21, a freind has one and I was impresses by how well it ran. It was easy to tune and ran 210 to 220 all day and probably better top end then the RG 21. If you're not going to do any organized racing there's a lot of good cheap big blocks out there also.