OK, did the web search and found a lot of info on Tmaxxeseses but couldnt find exactly what Iam looking for. I would like to install different engines in my Tmaxseseses and am looking for options and opinions. Seems to me the exhaust is the hard part but there are units available. So what engines would you use? I like OS but cant see spending $300 for an OS21TM. Ican see about $200 but not sure what Ican make work. It will need to be a pull start version so that limits selection quite a bit. I am not a big fan of electric starters.