What prop are you using for your Kadet (mines an LT-40). I use a 10/6 prop and im finding i have to use full throttle all the time.
I use an APC 10x6 and fly around at half throttle in my LT-40 with the OS 40LA. I go to full throttle for loops and Cuban 8s but that is about it. What altitude is your flying site at? Mine is around 1200ft or so. That might have something to do with it. I also fly off of a paved strip. I imagine if I flew from thick grass it might be more of a problem as well.
If I had the money I probably would have went with the .46 but the .40LA has been a good engine for me for the money.
JakeC