I designed and built a plane just for the .25LA. It's a good combination and placed first in it's first contest.  I have been testing other engines on the plane, O.S. Max-S .35 and the Brodak .40. I built a NMUEMP to install the .35 and .40 without carving the plane up. The Brodak .40, APC 10.5 x 4.5, tongue muffler and 3/16 thick aluminum universal engine mount is 0.9 ounces lighter than the LA.25, stock muffler and APC 9 x 4 propeller. I've stumbled on a match made in stunt Heaven.