But can you say "only game in town"? The AP is the only small engine I know that has a bronze bushed crankshaft. The crank port timing is milder than the Norvel, so the stunt run is really good.
With the Holuszko venturi, you have a reliable, powerful stunt power source. Norvels and Tee Dees may be more powerful, but in stunt, reliability and durability are the important things. I can always design a plane to suit the available power, and really, really like it when it stays in the air because the engine is dead reliable.
No, I don't make a cent by recommending this engine, in fact I have spent quite a bit on the ones I own. I just think it is the very best thing this side of electric for reliability.