Really enjoying the M Performance Interior Trim Kit.
Changes the entire look of the cabin.
Much better to my eye than the hexagonal aluminum, which came stock.
FWIW, my number one favorite mod; the mod I can't live without - is definitely the M Performance shifter. It completely changed the driving experience. Shifts went from rubbery to more rifle like. Shortened the throw up nicely, even though its only a third of an inch shorter. Go figure. Highly recommend it. Of course, YMMV.