RE: ARF Bashed GP 15-25 Combat Mustang
I put a Mac's black muffler like the one shown on my GP Spitfire/OS25FP combo, and lost almost 1000rpm. It does sound and look nicer than the stock muffler, and keeps more oil off the plane, but was a definite loss in power. Gotta get my TT .36Pro put in the Spitfire for some more speed!