The Extreme slaloms were pretty fast in their favorite conditions. If it is a 270, my experience with it was that the rocker is a bit flat for ultimate top speed on flat water. I tried altering it with tail cutouts but it didn't help for me. Still have it laying around somewhere in my historical artifact pile of stuff.

Your success depends on a few things:
-How tall/heavy you are. Bigger guys will have more success at cracking 40 on a slalom board.
- Where you try to do it. You will need pretty flat water and a broad course angle.
- How much wind you get. Even with the above two factors working for you, it is unlikely you can do it with much less than 30 Knots of wind. Sail size to suit.
Good luck with it. I like the Koncept a lot!