RE: looking to slow my trainner down without a new engine?
If you run a 10X5 three blade Master Airscrew you will have fantastic aero-braking for low, steady descent speed and lots of power to pull out of trouble without over revving. A side benefit is more ground clearance. Do not confuse this prop with an Evolution trainer three blade, I refuse to teach with those on a plane and install a APC 11X6 or black MAS 11X7.