I converted a friend Twinstar 2 by using:
- BL Motors https://www.hobbyking.com/hobbyking/s...dproduct=14739
- Propelers tri blade 7x6 https://www.hobbyking.com/hobbyking/s...dproduct=16711
- Esc turnigy 18A https://www.hobbyking.com/hobbyking/s...idProduct=2168

Installing the motors was easy: removing the Speed 400 and attaching the BL from their backplate and 2.5mm SHORT bolts on the original firewalls.
Ready to fly weight is 1033 grams with paint and a 2200 3S.
Power consumption full throttle is 19A. With a Nanotech 3 S 2200 we fly 10'30'' with mix of aerobatics and circuits (not trying to save the energy)

I installed a buzzer in the nose pointing forward and with the quite silent sound of the twin BL, we hear it from around 100 m away.
https://www.hobbyking.com/hobbyking/s...dproduct=18987

I find the performances a perfect ratio of investment/power/flight time/performance. 3 blade propelers are not the most effectives but we fly in unprepared fields and it offers more ground clearance than 2 blades