PatrickBW, I have the Sportwerks .21 in my Mugen truggy and I'm loving it. I put the Jammin JP1 pipe on it for alittle extra low end because I'm running in an indoor track. This engine really has some high end revs; I think the JP1 is a good balance for the SW21 and it may stay on for the bigger outdoor track this spring. I've had a few people ask, "what engine is that?!", and you know that's a good thing.