I know this post kinda went downhill, like all of them eventually but I'm back. What would you guys think of a OS .30, or Axial .32 in a Mammoth ST? I also need an engine that will be compatible with the Savage 21 Roto Start, just cuz i don't wanna get rid of it for the money I spent on it. (I don't have the money for a starter box) Thanks, and any other engine suggestions are greatly appreciated.