I personally think that red -or- blue -or- purple are worthy considerations for caliper colors on a blk/blk NSX. Silver (machined aluminum-look) -or- gunmetal (flatte) -or- bronze (similar the '02+ calipers and the 350Z/G35 Brembo's) -or- black (high-gloss) all are other colors that would look decent as well, especially w/ the "N-S-X" colored in a contrasting color.
I have a '91 berlina black w/ onyx interior, and I am in the same dilemma as to what color to re-finish my caliper's w/. I'm also going to subtly match my lug nuts to the caliper color... well so far it's just an idea, time will tell if I really go w/ it! :redface:
trust me silver is the best, I have silver on a red nsx but the color of the car doesn't mater plus i find it looks ugly and tacky if you match caliper and car. Matching the caliper with the color of your rotors is the way to go.
The good thing about the black is that it will hide brake dust and look good all the time. Obviously it wont stand out, but when someone gets up close they will notice how nice and clean it looks. My problem with bright yellow and red is that after some hard driving all the little contours of the caliper hold that dust on there and make your freshly detailed car, and wheels, look kinda nasty.