Aeroengr, Bit late to the party on this but was struggling to get my Seabreeze login working. Apologies in advance for the monologue...
I have been using a modified Starboard GTR set up fro about a year now. 95 carbon mast, 95+fuse, 800 front wing and the 255-2 rear wing. I have the original JP135 Hydrofoil (heavier epoxy sandwich). I sail on Botany bay in anything from 14-15kn with an old 8.4m Maui TRX up to about 22kn plus gusts with a 5.6m. Before this set up I had an original slingshot aluminium foil (older blue wings) that maxed out at about 23knots and was pretty scary. On the GTR I got 24kn almost straight away and worked up to 26kn back in February. Since then, I have been playing with a whole bunch of adjustments over winter to increase speed.
Rear shims: from -2.0 to -0.5 (noting that the 255 stab is already -2);
Mast track position: as far forward as possible for a while, but now backed off slightly;
Footstraps: Removed rear footstraps (about 4 sessions) for easy weight shifting downwind to control flight height, but found I really struggled controlling the board on the reach with only the front strap, particularly in stronger winds where you want to angle the upwind rail. They are back on now;
Changed footstrap positions AND angles; I squared the front strap up to move my front heel forward for more frontwards pressure but then my foot was getting stuck in the strap during gybes (not pleasant trying to yank your foot out mid gybe - tends to launch the board in an unwanted direction (upwards, sideways

).
Harness: started with waist harness, but much prefer seat harness for me as it allows me to create more mast foot pressure to control ride height.
Boom height: higher is definitely better for me, with harness lines spread wider than normal and front strap slightly further forward. Again I find this helps with really hanging on the boom on downwind runs to get the weight into the mastfoot to control ride height and take the gusts through to the board without sheeting out.
In/out of rear strap: I have tried both. Out definitely a LOT less scary providing the ability to quickly weight shift when the board rises too quickly (and the ease of rapid dismount

) but I struggle to get as much power from the gusts through the mast foot so try to use both straps whenever possible.
So after all of this, I got up to 27.4kn about a month ago which was pleasing progression. However, the 800 wing does feel like it struggles to accelerate quickly at this speed. So I ordered the 650 wing and a 115++ fuse from France which arrived early last week. Theory is that I can use the 115++ with the 800 in lighter winds with smaller sails (rather than buy a larger 1000 front wing) although yet to test that combo. Tried the 650 wing/95+fuse/255-2 with -0.5shim last Thursday with Dieter in about 20-24kn NEer using a 6.2m Severne R8 - we both did max 2s of 29.5kn! The 650 is so much quicker to accelerate in gusts, but also way looser. A few scary breaches, swerves and catapults when heading more downwind, one of which left me upside down about 1m underwater

. It felt like it preferred more broad reach with a bit of board angle to keep some pressure against the foil. My sailing style was
Bouncing Dolphin. Seemed much harder to control ride height, although it was pretty gusty conditions, so now need to try different shim angles.
Just watched a video that suggested more down haul with slalom sails for downwind runs.
Can't wait to get out again and see what's next.