Mm... lots.
Some sort of hybrid turbo, it's a small one. Big 28, I think.
2.5" custom turbo-back
15/16" rear sway bar
GC coilovers & camber/caster plates
16*7 or 16*8 shod in BFG G-force KDW's in winter
16*8 shod in R-comps in summer.
Shep trans (Stage 2, possibly 3)
DSMLink
Wideband
550's, possibly bigger now.
Water to air IC
Big brakes, 12" or possibly bigger.
I'm not sure how accurate that list is, it's possibly up to a couple years old.
It's a very robust car - I've never seen it break. It's great to drive (I did part of an event in it) - Very fast and responsive spool, extremely predictable high-g handling. He's had it for several years and it's very well sorted.