In my experience Katanas are particularly "high risk, high reward" discs. Even after you find a good one, it's pretty tricky finding the sweet spot between the high speed turn and the low speed fade. Yup they can be pretty, but they can also get you in tons of trouble. Some of my longest forehands were well over 400' with a champ Katana, but that disc also tended to get me in trouble because it had so much turn and would then glide quite well into places I never wanted to be. Sometimes, of course, I got into the opposite kind of trouble by not putting enough hyzer on it and fading out early.
Someone mentioned a Boss, and that's reasonable. Similar speed, but not such extreme high speed turn. Check out the feel, because it's quite a bit different from the Katana. You might want to try a Z Crank. I'd say I don't get it quite as far as that Katana, but it's a lot more friendly when I make minor mistakes.
It sounds like you're forehand form is not terrible, but I'd say make sure you can throw lower speed discs as well. A star Teebird has lots of forehand D potential, and don't forget things like Thunderbirds, TLs, or Surges. The longer I play and improve, the more I use my backhand for distance, but forehand for most approaches. In other words, try to make sure your forehand form works for all kinds of shots, from anny (right to left shots) to straight to hyzers/skips. That pays serious dividends as far as scores go.
