Stock exterior, H&R OE Sport Springs w/Koni shocks, possible swaybars, new control arms, M3 bushings, subframe busings, rear control arm bushings.
I like the 14" factory wheels, so I'll stick with them for now, most 15" wheels are significantly heavier so the 14's with good suspension is a nice setup. I might eventually get some Ronal LS wheels if I can find them, but I'm not in any rush.
Interior just the Momo steering wheel and a shift knob, that's it. Get a radio that looks decent and works with an iPod.
I like mine to look purposeful but non-molested.