Guys here are running OS25FX's and KY Mousse can mufflers with 8-6APC props. Great combo. Many are now using 30% fuel, but the actual measurable power gains are very small. 100-200rpm. Every little bit helps, but the power diff on this set up isn't worth it.

Fly better, shave off ounces wherever you can and you'll win more. 30% won't do it for you.