Oh yea, the YS is most definitely worth it. Gobs of power and torque. As an example, when I first got my Ultimate I had a YS91AC in it (used) After about 50 flights in shot the connecting rod. I started looking for the YS110 but no one had any in stock until another RCU member found one in CO for me. In the meantime until I got the YS110 I had a fresh Saito 120 lying around so I bolted it in and even though the HP figures were very close (the Saito 120 has 2.2 and the YS91AC has 2.0) the YS91AC blew away the Saito big time turning the same prop. Now I have the YS110 in which has 2.3 HP versus the Saito 120 and it smokesit easily.

And thanks I like mine to. I have my low rates at half and high at book throws and it's real docile on low and not to bad on high. I does have a couple of pitch coupling issues but nothing to bad. The first one is when the rudder is applied in either direction, the nose drops (pulls to the belly or called pitch coupling), The second one is also a roll coupling with rudder in either direction. When rudder is applied it wants to roll in the direction the rudder is applied.

I have mixed both of these out with the radio.

I flew two DP ultimates and did not see the tendencies as much as I have with the CG Ultimate, not that they are that bad to start with.

The YS140DZ has 3,2 hp
The Saito 180 has 2.8 hp

Oh and one other thing, all YS engines are fuel injected and supercharged and the tank is pressurized with a pressure setup that uses the crancase and a check valve to keep a constant fuel pressure (the check valve comes with the engine) so it will not matter where you put the fuel tank, I have mine right on the CG. That way the planes CG does not change as the fuel is burned off. To do that with the Saito, a few pump will be required. The pressure system used on the YS can also be used to pressurize a smoke system if you so desire. I read somewhere that a YS110 pressurizes the fuel tank at around 9psi. That seems high but they also recommend that you use fiberglass reinforced packing tape and wrap it around the tank to keep it from swelling.