A Comprehensive Look

In order to fully grasp the car as a whole, this is a basic itemization of modifications on the car currently.

Enigine
-ARC Super Induction Box
-ARC Titanium Pulley Cover
-ARC Titanium Radiator Cover
-C-West Carbon Fiber MAF Cover
-Cobb Access Port
-Cusco Heat Sheild
-NRG Carbon Fiber Hood Dampers
-Powerhouse Amuse R1 Extra Titan Exhaust
-Prova Brake Cap
-Prova Carbon Fiber Air Duct
-Prova Clutch Cap
-TopSpeed Protune 296 AWHP / 324 AWTQ
-Zero/Sports Catted Downpipe
-Zero/Sports Intake Pipe Kit

Drivetrain
-Cusco Hardened Motor Mount
-Cusco Hardened Transmission Mount

Exterior
-Chargespeed Carbon Fiber Type 1 Front Lip
-JDM Number Plates
-JDM Wakaba Beginner Driver Badge
-STi JDM Clear Headlights
-STi JDM Clear Side Markers
-STi JDM De-badged Trunk
-STi JDM Rain Guards
-Subaru OEM WRX Side Skirts

Interior
-ATI Gauge Pod
-Autospeed Dead Pedal
-Bride FO Seat Rail
-Bride Zeta II Driver's Seat
-Cusco E Con Dampening Controller
-Defi BF Amber Boost Gague
-Defi BF Amber EGT Gauge
-Defi BF Amber Oil Pressure Gauge
-Defi Link Control Unit II
-HKS Kansai Service Low Position Seat Rail
-Nardi Sport Rally Deep Cone 350mm Steering Wheel
-STi JDM Auto Intercooler Switch
-STi JDM Door Sills
-STi JDM Floor Mats
-STi JDM S203 Red Hazard Button
-STi JDM Spec C 12L Intercooler Tank
-STi JDM Spec C Carpet
-STi JDM Spec C Door Cards
-STi JDM Spec C Front Seats
-STi JDM Spec C Rear Seats
-Zero/Sports Formula Starter Kit

Braking
-Cusco Master Cylinder Brace
-Hawk HPS Pads [Front]
-Hawk HPS Pads [Rear]

Suspension
-Cobb Front Endlinks
-Cobb Rear Endlinks
-Cusco Front Strut Tower Bar [Titanium]
-Cusco Front Sway Bar [22mm]
-Cusco Rear Strut Tower Bar
-Cusco Rear Sway Bar [Adjustable]
-Cusco Zero-2E Coilovers
-STi JDM Spec C Forged Aluminum Front Control Arms
-STi JDM Trailing Arms

Wheel / Tire
-Falken RT-615 255/40/17
-Project Kics R40 Neo Chro Lug Nuts
-Yokohama Original Wheel Design Advan Racing Center Caps
-Yokohama Original Wheel Design Advan Racing RG 17x8.5

Hopefully it's already evident that the intent of this project is quality and substance over quantity. Further I favor response based tuning, and will make every effort to shed weight and sharpen response over directly increasing power. To this end I break the car down into a somewhat narrowed list, expanded with weight comparisons of both stock and aftermarket pieces. Huge thanks to anorexicsti, whose work has helped fill in data for stock pieces that I have misplaced or even failed to weigh. I left the basic format the same as the modlist, should anyone want to quickly reference something, aside from that I list the total weight savings or weight gain, then bracketed behind that number are the weight figures for the stock part and then the aftermarket replacement. Straightforward as could be.

2004 Subaru Impreza WRX STi - 3298 lbs

Enigine
-ARC Super Induction Box - 2.0 lbs [10.0 - 8.0]
-ARC Titanium Pulley Cover + 0.25 [0.5 - 0.75]
-ARC Titanium Radiator Cover + 0.5 lbs [0.0 - 0.5]
-C-West Carbon Fiber MAF Cover + 0.2 [0.0 - 0.2]
-Cusco Heat Sheild - 0.75 lbs [2.25 - 1.5]
-NRG Carbon Fiber Hood Dampers - 0.0 lbs [1.25 - 1.25]
-Powerhouse Amuse R1 Extra Titan Exhaust - 20.0 lbs [32.0 - 12.0]
-Prova Carbon Fiber Air Duct - 0.5 [1.25 - 0.75]
-Zero/Sports Catted Downpipe - 10.25 lbs [23.25 - 13.0]
-Zero/Sports Intake Pipe Kit + 0.5 lbs [1.25 - 1.5]

Drivetrain
-Cusco Hardened Motor Mount - 1.5 lbs [3.75 - 3.0 x 2]
-Cusco Hardened Transmission Mount - 0.0 lbs [3.0 - 3.0]

Exterior
-Chargespeed Carbon Fiber Type 1 Front Lip + 4.75 lbs [0.0 - 4.75]
-STi JDM Clear Headlights - 0.5 lbs [4.0 - 3.5]
-STi JDM Clear Side Markers + 1.0 lbs [0.0 - 1.0]
-STI JDM De-badged Trunk - 0.25 lbs [0.25 - 0.0]
-STi JDM Rain Guards + 1.25 lbs [0.0 - 1.25]

Interior
-ATI Gauge Pod - 1.25 lbs [3.5 - 2.25]
-Autospeed Dead Pedal + 0.25 lbs [0.0 - 0.25]
-Cusco E Con Dampening Controller + 0.25 lbs [0.0 - 0.25]
-Defi BF Amber Boost Gague + 3.25 lbs [0.0 - 3.25]
-Defi BF Amber EGT Gauge + 3.25 lbs [0.0 - 3.25]
-Defi BF Amber Oil Pressure Gauge +3.25 lbs [0.0 - 3.25]
-Defi Link Control Unit II + 0.5 [0.0 - 0.5]
-STi JDM Auto Intercooler Switch + 0.25lbs [0.0 - 0.25]
-STi JDM Door Sills + 2.0 lbs [0.0 - 0.5 x 4]
-STi JDM Floor Mats - 3.75 lbs [9.0 - 5.25]
-STi JDM S203 Red Hazard Button - 0.0 lbs [0.25 - 0.25]
-STi JDM Spec C Carpet - 1.15 lbs [7.15 - 6.0]
-STi JDM Spec C Front Seats -30.0 lbs [90.0 - 60.0]
-STi JDM Spec C Rear Seats - 2.0 lbs [20.0 - 18.0]
-Zero/Sports Formula Starter Kit +1.25 lbs [0.0 - 1.25]

Braking
-Cusco Master Cylinder Brace + 1.0 lbs [0.0 - 1.0]
-Hawk HPS Pads [Front] - 0.0 lbs [2.25 - 2.25]
-Hawk HPS Pads [Rear] - 0.0 lbs [2.25 -2.25]

Suspension
-Cobb Front Endlinks - 0.0 lbs [1.0 - 1.0]
-Cobb Rear Endlinks + 0.25 lbs [1.0 -1.25]
-Cusco Front Strut Tower Bar + 2.0 lbs [0.0 - 2.0]
-Cusco Front Sway Bar - 2.0 lbs [7.0 - 5.0]
-Cusco Rear Strut Tower Bar + 3.5 lbs [0.0 - 3.5]
-Cusco Rear Sway Bar - 1.25 lbs [8.25 - 7.0]
-Cusco Zero-2E Coilovers - 21.0 lbs [20.0 - 14.75 x 4]

Wheel / Tire
-Project Kics R40 Neo Chro Lug Nuts - 0.25 lbs [1.25 - 1.0]
-Yokohama Original Wheel Design Advan Racing RG 17x8.5 with Falken RT-615 255/40/17 - 20.0 lbs [45.0 - 40.0 x 4]

So in conclusion, building a livable and trackable street car with weight savings as a priority not a goal has left me with an STi that weighs in at 3208.80 lbs, or a total savings of 89.2 lbs. Not bad at all.