Idont like magnum, asp, ph, sc .25 engines.
Weston is high guality beautiful engine, but it is strong only with somekind of tuned pipe.
My best osfx.25 with some tuning work and hatori muffler revs 15900rpm 15% nitro apc 9x5 prop.
But iuse engines aces 1:12 combat planes , rules determine the muffler size, type, prop size, max ground rpm and all type pipes are prohibited.