I only went Stg2 with my WRX, and now that I have an STi I plan on keeping it for the long haul and going quite a bit further than that, so here is my current progress. 3,200mi on the odo.
2013 STi Hatch
STi Short Throw Shifter
Heated Seats and whatever else the STI hatch comes with (BBS wheels
JDM STi Front Lip Spoiler
Black JDM STi Side Badges
Plastidip on the wheels, currently matte black
Cobb Turbo Heat Shield
Edit: Cosmetic/Functional Mod: RallyArmor Mudflaps <---Best mod on my car to date
Invidia Catless Dowpipe
Cobb Accessport running Torqued Performance Etune
FMS Front Mount Intercooler
I plan on eventually swapping to a Blouch 20G, so everything up until now plus my next couple mods are all preparation for that.
Next mods will be:
Fuel Pump - DW65c
Injectors - ID 1000s
Clutch - Still undecided, but probably ACT 6 puck.
Turbo - Probably Blouch 20GXT-R
Headers - Equal Length
Rear Sway Bar
Driver mod - hoping to take some performance driving classes
Protune(s) as needed
I don't want to start thinking about a shortblock right now, but I see that in my future so I'm saving now just in case.
This is probably the most vanilla build plan you guys have ever read, but from my experience it's much less headache going with what's already tried and true rather than trying to get unique or do things on the cheap. On that note, I'll be writing about my FMIC install saga shortly.