pretty much all the essentials but the turbo upgrade, dv, tip, fmic, turbo back exhaust, cai
but i ran HB6 with no fmic and it was still happy. i get abit of timing pull, but this is more likely due to factory spec plugs or just poor quality fuel
boost tails off no more than it did on HB6 so i left it, always within 21/22 on spike and 11psi at redline
car feels great when it wants to