Hi, Bob,
We're using a new DS 54, outstanding stunt engine! Put it in an old Steve Buso Heatwave, 64 ounces, 660 squares. Using 12/5 or 12/6 wood props, regular Powermaster 10% fuel(not the GMA), stock Sig plug. Beautiful 4/2/4 character, excellent power and starting "friendliness". This engine is at least as good as my BEST ST 46, probably a little better. We also have a new DS 40 BB in a JD Falcon, similar outstanding results!