How far did you throw before the Katana?
The Valkyrie was my main driver and I felt confident in the 325 range however could push it out to 350-360 but accuracy declined.
All the Valks that I threw were 175. I got a Katana at 175 though and it just didn't work for me. So I dropped down to a 168 and that thing is magic for me.
I have been practicing in the field for months, using a Dynaflex 2-3 times a week, and was getting frustrated as it didn't really seem to make a differance but when I started dropping down in weight, and slowing down during my run up and throw the disc started going farther.
Now when I go to the field I take a handfull of 155 Gazelles, and some putters. The lighter discs teach me snap and the putters teach me spin.
I am also 6'2" and lanky. I think that the arm length may help me with distance.
Also if you played me you would see that the extra distance doesn't really mean a better score. On a hole that is 380 I may be able to get the Katana there, however most of the time it is to the left or right of the hole 40 feet, I don't make many 40 foot putts but I will take an easy par. The next guy throws a 300 foot shot, then an 80 foot upshot, and we walk away with the same score.