Lynx and spaceman:
Thank u, I feel that the TT 39 power is not sufficient for me, I'm not planned to upgrade my heli, but definetely want more power on it. The TT39 is good engine anyway. I planned to try my first loop this week, and inverted too :-) but I feel that the heli not responsive enough.
I run 15% nitro (cool power), I think I will try 30% before try to upgrade the engine.

440GTX:
Honestly, I can order it from Singapore. But sound ridicolous if everytime I crashed, I must grounded for about 1 week waiting for part. But I think I can stock 1 crash kit here. My crash log right now is at 3 times :-).
I will think all over again.

Albertus