I haven't used them, but they are on the way, and I'm doing a mild drop.
This company makes these pieces for other retailers, including BAT. It is the same piece.
You don't need them because you'd be changing your ride height. You need them because you have 2 degrees of negative camber, because the GC setup lets you run with very aggressive drops, and because your alignment is not consistent left to right and will probably never be so unless you bolt on some more adjustability.
