There are several mod categories. This is my (incomplete) list:
5) improved safety
Each owner will have different priorities based on how the car is used. A daily driver (DD) would prioritize different than a track car. For example if your are driving 6 miles to and from work each day a super charger would probably be a waste, but better brakes and improved mileage mods would be high on your list.
So my suggestion is for you to prioritize your desires and then ask in those areas.
That said (and depending on mileage) you should probably have an upper induction cleaning done and put a catch can on now.
Mods: GM Locking Gas Cap, RS License Plate Frame