Maybe a set of darker wheels, maybe black to keep with the black matting and Shinoda decals.
Also any extra work done to the brake system? maybe some painted calipers? Hows the interior look?
On one more note, maybe offer the HID headlight kit, moves the main bulb closer to the hood pillars like a 70 Boss. Makes it feel a little more retro, and it also places the blinkers on the outside which can be barred accordingly.
Lastly, perhaps a more defined air dam
For reference:
Other than that superb job guys, looks beautiful. It's a Shinoda through and through!