Wow, you are getting serious with the build! I have the exact same car to include the fastest color - "Lightning Red" so I will be watching this thread for updates! I also did not purchase the Premium nor the limited because the options added a lot of un-needed weight. I am actually on the fence on removing the Air Conditioner unit to include the AC radiator - still debating this one as I have not found any data on how much weight that will reduce. Don't really need AC during mild Seattle Summer not to mention I ride my Hayabusa during the hot months.
My build is going towards weight reduction with performance.
1. Lower suspension using Eibach springs - reduces a pound or two
2. O.Z. Alleggerita HLT 18x8 wheels at 17.4 lbs vs OEM Wheel at 23lbs
3. BG Goodrich g-Force T/A KDW 2 235/40ZR18 - I live in Seattle where it rains from Oct to May so need a tire for wet. Tire weight is 23lbs versus OEM Tire at 24lbs. The new 2011 WRX runs the same wheel size with the same drivetrain so there should be no issues going .5 inches taller.
4. 5Zigen FORGED RACING LUG NUTS reduces about 5oz per wheels over OEM
5. Invidia Q300 single exhaust should reduce another 25lbs or so.
6. Invidia Down Pipe
7. Perrin Pully reduce another 4lbs
8. Currently running full synthetic Amsoil in motor, but will be running Amsoil synthetic in Transmission, front and rear diffs
9. Perrin Turbo Inlet Hose
10. Perrin Afta-MAF Hose
Overall I suspect I will lose ~7lbs per wheel, total of ~28lbs
Total reduction of weight to vehicle will be around 60lbs
Total HP/TQ gain ~20HP/20TQ
I plan on keeping the intake stock for now too, with the exception of the H&K drop in filter I added in which I noticed very little gains other than 1MPG better fuel economy and maybe a hint, just a tiny hit of better throttle response.
Car is also debaged with the exception of "WRX" on front and rear to include the big blue Subaru Logo.
I don't have much planned other than that for now because I don't want to mess with the stock tune quite yet.
The last weight reduction will be me at 235lbs at 6ft to get back to my 200lb frame! LOL!
The hard part is justifying all these upgrade with my wife as she does not understand why I need a fast car when I already ride a 2008 Suzuki Hayabusa with 200HP no to mention I only drive my WRX when it's raining. Car is 6 months old and only have 1,900 miles on it.