First with isonic 70. Good but not full powered. Some nice runs and the best 250m at the day. Vmax 34.1 knots

Then I compared with the isonic 90 and  sonntag gps 6 30 cm. Constant speed (32-33 knots) and good run with 34,7 vmax. 

Both boards worked well but I felt better with isonic 70 because it needs less legs works :)

Nice day!

4 kg extra weigth