Super Tigre makes ABC, let me correct that, Super Tigre invented ABC, and you can get them in .45 and .61, and they run stronger than the OS counterparts, every time. Super Tigre's are excellent engines in competent hands. Many blame an engine instead of the bad configuration on their plane, using wrong fuel, prop, glow plug, running with the tank high/low, and not tuning the low speed mixture. I know many OS users failing to get a screwdriver out to adjust their idle mixture for better transition all the time, and think the main needle will somehow miraculously take care of everything. The one and only tuning nightmare I've had, was with Fox engines, and gave up about 20 years ago on them.