Well, since I seem to be the only person in the world to have tested one of these, 13,300 rpm with a 7-5 MA GF series 3 prop, 10% fuel with muffler, 15,700 with no muffler, 17,200 with an opened venturi to .240". I made a Turbo plug head and with the opened up muffler it went 17,100. That is almost as good as the OS LA at 17,400 with no muffler. The LA is really quite a good motor for what it is. It idles better too. The AP .15 is a bit smaller than a .15, working out to a .135 or so. It is made from the .09 case, so the crank hole is small, as is the muffler and carb. The AP .09 is really pretty good, but the .15 suffers a bit. Having said that, it is a fairly small and light motor that gives a bit more power to a smaller plane. The ASP .15 is almost 2 oz. heavier, but puts out 17,600 rpm with no muffler for maybe $45. I found it easier to get some performance gains from the ASP compared to the LA if that is what you like to play with. The LA is more money as well, but more consistent in quality control. Oh, and the Fora puts out 20,500 rpm on the same prop, I could match that with a Turbo head I made up on the ASP. Hard on plugs though.