THAT'S exactly what I was going to say. The easiest and most practical way to get more power from a model engine is to buy a BIGGER one. Or even the same saze with a higher output like going from a 40FP to a 40FX. No chance of ruining an engine or voiding the warranty and it sure is easier. If you like hacking on engines and don't worry about wrecking one, have a ball whacking on one. Adding a tuned pipe will give you more power without damaging an engine also.