Hi Maximus.
I did 28.6 knots on a Carve 145 with a 9.4 Tushingham Lightning/45 cm weed fin, once with a Garmin e-trex. Dont know if it was for 2 seconds though...

Guess there's a difference between a max peak and constant (2 sec) max...
A Hyper with 8.5 should easily be able to do +30 knots with an 8.5 in the right conditions....