I saw a set of these MASS 205MB wheels the other day.They are carbon flat black which look different. But the FRPP Bullitts in black are nice for the price between $155.00-$165.00 each which have a nice gloss finish.(my 06'GT with the FRPP Bullitts)

http://www.maaswheels.com/images/205MB_M205.jpg

 

do a photoshop or ms paint picture of your stang...do 2 of them, 1 with black rims, the other with gunmetal rims, and see what you think...thats the best way to see what it looks like if no one else already has that combo....you never know, u might not like what u think might look good and its better to find out now before you go and spend the $$$ now and then hate them later....

 

here are a couple of old pics when mine was all silver with dark grey wheels and matching stripes...

 

Black wheels not lookin good? What?... I beg to differ...

 

If 06elnr's car is the same as yours, than id say that dark grey wheels would look awesome as well...all in all i would venture to say that it would just boil down to what YOU overall!