Do you know if your motor is the original version or the 'V2'. It's reasonably easy to tell, the V2 has a cooling fan built into the end of the motor. See photo here: http://www.aero-model.com/Hacker-Brushless-A30-14L.aspx

The original type motor just has a plain end plate, like the one pictured here: http://www.marionvillemodels.com/rc-shop/haker-brushless-motor-HAK-A30-14L.html

The V2 motor is rated for 50 Amps so should be safe in your application. The ESC might be on it's limit but if well cooled might be ok. What brand is the ESC? You may want to try a Xoar (or JXF) 14x7 wood prop, rumour is they pull a few less amps than the APC. I'm running the A30-14L V2 with the Xoar prop in a Precision Aerobatics Ultimate AMR. I'm getting 2 - 2.2Kg of static thrust which on a 1.1Kg model gives great vertical performance. What does your Katana weigh? If it's much over 1.5Kg then the vertical is probably not going to be stellar, going to four cells and a smaller prop would certainly pep it up (without increasing amps).

If flying with lots of open throttle you will be limited to maybe 5 minutes flying, i can get over 8 minutes of general sports flying out of my AMR with the same motor and same 3 cell 2200 battery.

Hope this is of some help
Steve