I agree with Jadda that the CEN NT 16 is a good base engine. I have my two originals and they still perform very well for a beginer intro nirto engine.
I have been testing other engines just to see for myself what works good with the MT2 chassis design. The only thing I find puzzling is why does the NT 16 have a restrictor sleeve in the base of their carb. I plan on removing it this weekend to see how it effects the NT16's performance. I believe this engine could be a performer if it was had all the high RPM breathing tricks done to it.