I've yet to install mine either (for a GS, 16"), but I have had it in place a few times, requires some trimming of the plate itself near as I can tell. Older jackplate on mine as well, so I'd also be drilling to mount the side plates. Not a really a big deal, just haven't found enough time to get on it.
I think part of it too is the thing launches so well with just the Allison cavitation foil, I haven't felt the need.
But I do recall seeing quite a few out here who have installed them.