Onr thought to keep in mind, as you move up in HP. On a 5 speed the gear set with 25 teeth on both the drive and the driven gears are the strongest, that usually 3rd. In 5th you go up on the drive gear (say 40 teeth0 and down on the driven (say 10). The smaller gear is weaker that the bigger gear. When in the 25 to 25, both have the same strength.