Whatever they did to this car, you should match part for part.
It just doesn't show the speed holes on the rear bumper!
LOL JK
I think the SG/UG/Bluetooth gauge is the best thing and should be of highest priority. Not only will it help you determine best driving practices, but when you do mods, it will help determine how beneficial they will be.
Take a stroll through the Aerodynamic sub-forum and you'll find a ton of mods that you can pick and choose from based on what you think will look good. Some things to do without changing the 'look' (or only a little) will be belly pan, rear diffuser, air dam, internal grill block, etc.