Seen so many of these cars in the flesh and never paid that close attention, usually end up drooling over engine and bodywork haha. Will pay more attention next time but for now here are my thoughts:
wheels I thought these were about these sizes: 12x18's for the rear and 8x17 fronts. The IMSA 320 turbo even went beyond that with 14x19" at the rear and 11x16" at the front. IMSA specs according to supercars.net even though a 3" difference in diamater front/rear seems odd to me.
subframes: also need to take a closer look but I guess those are customs with uniball.