Ok, both a 450kg and 600kg max take-off weight requirement I do understand as that is the European two seat microlight and LSA regulatory limits. A sport pilot licence weight limit I understand too. A price point is another as I see valid requirement. Still, buying second hand negate part of this. But an installed horsepower requirement? Yes, for a part 103 flying vehicle, but less that I do not know about some regulation on installed power. Neither do I know of a country that taxes airplanes by the engine size. Then, why a horsepower limit?