The best thing about these is the cheap fuel. I don't know about over there, but here we can run those all day on just a couple gallons.
As for petrol (gas) engines, they are just as simple as the ones in a nitro heli or plane. However the carb is more complicated and you have reeds in the intake that you can change to bring power onto the pipe at different times. and speaking of the pipe, that is what will make the power out of these engines. They are a blast to drive and sound great.
What size is the engine? I'm guessing 49cc since it's a 1/5th scale.