I have one with the ST G90 on it and love it! Incredible power and a blast to fly. A friend just got one and bought the Tower 75 and I am amazed by the power that engine has. The engine is a little lighter and is an ABC engine vs. a cast iron liner with a ring. I have a radar gun (for my work) and that Tower engine will run the Stick around 101mph vs 103 for my ST G90. The Tower is easy to break in, runs well out of the box, and is definitely easy on the wallet. A word of caution - change out the nylon wing bolts often or use steel and fender washers......ask me how I know this, it was rather spectacular but it is about ready for the air once again!