IMO, I wouldn't go that far unless you have more proof than that thread linked with the shock, spring, and stabilizer bar part #s .
I consulted the same book, and to be more specific than the OP was, it gives part #s for front and rear lower control arms for upgrading a base (FE2) solstice. For a GXP (FE3) solstice, the lower control arms are already on the car (production part).
I checked out a few parts websites and 2 lower control arm options are listed for any given corner for a base fe2 solstice, which agrees with the book. Can't see the part #'s though.
FWIW, the part #'s given are for l/r of the front and rear, if you want to break them out and check.
I seem to remember lower control arm differences from the base to the GXP too, discussed back when the GXP first came out. Maybe I'm wrong though.
So to the OP, there is no lower control arm upgrade from FE3 to Z0K.
