I came across this little motor at hobbypartz.com for as little as $40.  I wanted the 25 for the torque but this little one seems to work very well.  Weighs about the same as an FP25, but with a smaller, lighter muffler.  Of course is needs a new venturi and needle valve assembly.  I used the OS NVA in a home made venturi.  Just find a buddy with a 10inch lathe.  Sanye Mfg. seems to have come a looonnng way in quality since the last Magnum 35 I bought a few years ago.  This motor was very clean, tight, and seemed to have excellent machining and casting.  After about 30 runs is still is sqeaky tight right around top dead center.

I put it in place of a Thunder Tiger 25(nearly identical weight) and broke it in the modern way- multiple fast, rich runs on a 8/4 APC prop until it settled down and would hold a setting.  With a .265 venturi(LA25 size) it could make a good combat motor.  When set rich it would break into a screaming two cycle in a maneuver and then settle back to a 4 in level flight.  Finally ended up with a .235in venturi and a 10/4 prop.  This runs about 9800rpm on the ground, doesn't speed up much in the air, and has a fairly soft break with moderat speed up in maneuvers.  The motor is very easy to start and runs very steadily.  57-58 ft lines giving a 4.8 sec. or so lap seems about right for a 29oz. plane.  Sucking fuel out of a Sullivan SS-4 uniflow tank it takes about 2.5oz of fuel for 6.5 minutes.

Since the muffler is pretty small and short a little longer custom muffler may give more "tuned pipe" like results.  I believe it would work well on most 400+ profile stunt trainers.

I have a .15 sized ASP Hornet.  While I haven't flown it I have been very surprised and impressed with how well it bench ran.  Two flip start, one flip restart.  The settings were pretty close out of the box.  I was going to stick it on the nose of an old jr ringmaster with the throttle wired open, but haven't yet.  It is significantly lighter than a Fox 15BB (but what isn't lighter).

Phil