Let me start by saying I think the definition of extreme 3D is subjective some guys are using the OS 160, which flies it like a foamy, or more of an engine with wings...

So instead of saying buy this engine or buy that one I will just give a performance report. Can this plane with the 120AX combo do any maneuver traditional or 3D? Yes, absolutely without question. Pullout power is great, I can hover/torque roll with the 120 at about 1/3 throttle spinning an APC 17x6, (peak RPM with this combo is about 9000 at about sea level). Since the RPM max is 9500 I am going to try an APC 16.5x5 to see if I can gain a few more RPMs and improve throttle response. It takes just a hair longer to spool up than I like for super low 3D so I'm hoping this is an improvement in that area (I am pickier than most guys though). Overall this engine has amazing power, it is ported differently than the older 108, which had a higher RPM but less torque. I hear it was built to be a newer generation 2 stroke designed for today's flying styles (3D High Alpha) and to give the 4 strokes a run for their money. From my experience this has been the case plus the added benefit of fewer internal moving parts on a 2 stroker and it burns cheaper fuel; I use 15/15 PowerMaster.

You can also see pictures of how well this engine fits in the ST in my post on page 65 post number 1622. I love the fact that the lines are still clean and I don't have a huge muffler hanging out the bottom (except my rubber deflector).