If you really, really, believe that you will need all the horsepower potential that you can get from a small glow engine, go out and spend a whole bunch of money on a Dubb Jett racing 40 with a tuned pipe. Expect to blow a glow plug every other run or so, and they will be special glow plugs that will be rather pricey. Also expect to be tuning the pipe all the time in the never ending search for the "perfect length" for maximum. You can also plan to be spending a lot of time figuring out how much to shim the head for the fuel you intend to run. You might also have to mix your own to get it "just right".

While you are doing all this, your friends will be out having fun flying with their stock engines and thinking you're nuts.

The other option is to go purchase a good .60 size engine to get more power. Cheaper, faster, and easier.