RE: How do I get my Isonic 125 faster..
I have found on my 122 that i need the base all the way forward for my 9 and a few cm's forward of centre for my 7.5. The 122 now comes with a 38 & 44cm fin suiting these sails perfectly for my size(105kg). I would reccomend getting something between 38 & 40cm for your 7.7.
I don't find I go a lot faster on the 7.5 compared to the 9, 9m/44fin - 30(55.5km/h) 7.5/38fin - 31.7(59km/h) but i am still getting used to the board and this is reaching in normal chop.