RE: Ian- What size fins for iS87?
I'd think you're gonna be pretty happy with that one.
Focussing on speed with the iS87 on 6.4m, riders in the 80-90kg range should consider a really good 30cm, which will also double as the 5.8m choice up until it really starts nuking, when for pure speed you can consider a 28cm (which would then be the choice for 5.2 conditions as well). (Race fins in equivilent range/performance sizing to stock)
in this case, going for moderately stiffer fin in the smaller (speed) tuning is usually a good thing; the fin will be less user friendly at low/mid range but more reliable where it counts- at the top end when pushed.
It is possible to run smaller (or more raked or lower A/R) fins - which will result in a smaller "mechanical" (measured) size, but selection/sizing of these would equate to equivilent "performance" size to the above benchmarks.
On the iS87 for speed, but it's also possible to under fin the board relative to the conditions (the board is very sailable "early" in the speed range on (say) 28cm ) but typically the best results come from running a little more, rather than a little less for the given conditions.
I've not been there, but that Ray looks pretty promising, so you should be in good shape to get some solid new PB's.
Have (fast) fun !
Cheers ~ Ian