I installed my Shaftworks USA tuned OS Giken Super Lock LSD this past weekend! Install went smoothly and no leaks. Here are some install pics, my feedback so far (very very limited feedback) is below.
Subaru *can* use the correct amount of RTV, wow!
The break in instructions for the diff, which explains the lack of meaningful feedback
Ring gear all torqued on with orange threadlocker in lieu of the stock locking tabs. Marked for future inspection.
Diff backlash checked out perfectly in spec, at the tighter end but NBD. The diff has less whine on decel now, haha.
Waiting for the cover sealant to cure, bored...
Installed a polyurethane shifter bushing, mostly because it was cheap. I've noticed no meaningful difference.
So for some initial feedback... With the caveat that I now have ~15 miles on the diff (of the 1500 street miles for full break in) and I'm using Motorcraft fluid, not the fancy OS Giken fluid.
The diff chatters bad on power in tight corners in my neighborhood but does not when coasting. I assume this is mostly just the oil, my ND Miata was silent and smooth as silk.
Feels awesome when attacking, drifts are super progressive and less snappy. When it's not drifting it just carves the line you picked, like it did on my ND. So you're on a line and you get on the gas and the nose almost wants to tuck itself in to counteract the natural push.
Seems to put power down better too, duh?