I have tried a fair range of high quality fins over the last two years. I use high quality sails KA Race 2012 sails and Naish boards SP ltd 95 mostly.
One fin that I can recommend everyone not sponsored by other brands that I keep using myself, if your peak speeds or confidence at the top end speed is not improving?
Is the Vector 32 Rocket perfect for your high wind slalom board. last weekend in rough water this fin held strong in 5.5m KA Race sail conditions to take me over 37 knots

. also gybed so well over 23 alpha in rough water.
The best thing is the control and limitless speed and confidence I get at the top end deep off the wind.
They can be purchased from Jasper Orth

for
$230 worth every cent.
www.vectorfins.com.au/fins/slalomCheers Russ