[Flyinrazrback]

The 24x12 is too small, and since you are running the pipes, you can probably pull a 26x12, however the air models or mejzlik 25x12s (and the fuchs 25x12) are all good props, I would go with the smaller 25x12 just for the extra thrust since the yak is a draggy airframe. One thing to consider is the yak's cowling is very wide, and how much blade you will have past it using a 3 blade, for that reason I used a 2 blade on mine. If you want a prop that pulls well and still a 2 blade for imac, try the 3w 27x11 carbon prop, it is wide, quiet, and pulls well, and good downline braking too. I and a friend ran mejzlik 29x10s on our yaks with a 106. I also hear the Vess props are money too.