well you can put a larger diameter smaller pitch prop an a 2 stroke and it will give a bit more low end power. i have a 13x4w turning 11,800 rpm on my tt61pro and it does great. it does better with the regular 13x4 at 12000 rpm and quicker spool up, but the LHS didnt have any last i bought.

this set up is on my UCD46. and i love it. although the 4stroke arguement is a good one. having an engine that will work well. is better than buying an expensive 4stroke, just to say you did.