Whatever reasonably light, reasonably priced 13x6 et 13-25 4x100 wheels I can find.
Currently Superlights and an old OEM BMW wheel. Both are in the 12# range. Would love to get in the sub 9# neighborhood, but not willing to spend the $380-$420/wheel price that the Volks and custom wheels cost.
New option I'm looking at is Spin Werkes (formerly Circle from what I can tell) custom multi peice.
For another FP project we have been searching for a good light (light is a huge priority on this one) 13x7 with 4x100, and offset in the 30s. At this point looking at Spinwerkes for that as well.