You may want to go to the gas engine forum and see what other guys are saying about the different engines. The flying bricks come out about the same as most other gassers after you weigh the newer engines with there ignitions, batteries and switches. Then if something breaks or goes wrong it's also nice to have someone to go to for help or parts. Anything over A 26 on A 1/4 scale cub is over kill. I had the RCS 1.40 22cc on mine, that wasn't A bad combo. My Brison 2.4 40cc gasser in an 80 inch 15 pound Sukhoi worked out well with the Zinger 20X8 but really came alive with the Xoar 20X8. Props are just something you have to try to find that magic one.