I have one of the ASP 91 red heads and it runs great. Usually starts with one or two backflips. It has a lot of compression and will bite you occasionally if you handstart in the conventional forward direction. Also, some people have found it necessary to run it with a head gasket, especially if they like to run nitro in their fuel. In fact, mine came with one included in the box. I never installed it as I rarely run more than %5.