Hi,
I can recommend the MVVS 49 as I have very good experience on this engine. I was running a fullenght tuned pipe on the MVVS 49 and the engine is very reliable. APC for propps, 11x6@13400, 11x8@12500, and 12x6@12000rpms is what I got. Good throttle response. I am sure on small propps it realy screams. A friend of mine has turned his MVVS 49 17"+ on a APC 10x6 and unmuffled tuned pipe.
Good luck, Amir