I'm getting ready to put up a lengthy post in the ARF section on this very subject. The short answer: The GSP Katana is a phenominal 3D flyer and the OS 1.60fx is THE PERFECT engine choice. I had issues with the wing strength...some buckling occurred in flight when doing a 'wall'...I've never seen a plane near this size that would do a wall so well. I'm going to contact GSP in a few minutes and see what can be done about the wing.

-Tom