Hey ash, got some pics of your ride up buddy?
Sounds like you're setup for decent power on the street, have you done any suspension/brake modifications? How about sydneykid's suspension setup for your R34.. including LCA, camber kits, subframe alignment kit, struts etc. Perhaps get in on the R34 slotted/groove rotors with EBC green pads for some brake work. Hopefully that'll let your car rip through those hills.
Cosmetic wise, if you want to enhance the standard lines of your 34.. perhaps an East Bear lip and perhaps rear diffuser? That'd set it totally off with the right set of rims.