Way late to this party… but here goes.
I bought an ‘04 STI new in late 2003 when they first arrived at the dealer’s showrooms. I finally found a deal at MSRP, whereas many dealers were asking for a significant premium over MSRP, which I simply wouldn’t accept. The car was blue with silver wheels, and I was blown away by them being delivered with what effectively was R compound tires.
First track day with the STI was at Lime Rock in March of ‘04, and it was a day with both dry and wet sessions. My STI was the only one there. I quickly took to its driving dynamics and had a blast on the circuit, which was just about ideal for the STI. By ideal I mean that Lime Rock is fairly tight and somewhat technical, and with only one long-ish front straight where the higher HP cars could get by. In the wet, there weren’t many faster cars at that early date.
The stock STI’s secret weapon was its cornering ability. You could dial out any 4WD corner entry understeer by entering the corner fast and trail braking right down to the apex. The car reacted so well to that. Then its ability to slingshot from the apex out with all four corners scratching and growling for traction was a revelation for me. Still makes me smile today.
Niko, I took my STI in a very different direction from what you are planning. I made no mods to the car aside from better brake pads, tire changes and frequent fluid changes. Nothing. Instead I decided to devote any upgrade dollars being considered to doing more track days. I guess you could say I was developing the nut that holds the wheel (smile).
A set of dedicated Blizzack tires/ wheels for winter driving made the car nearly unstoppable in anything up to bumper height snow. Truly a rally car for the street.
I drove 30 odd track days at numerous circuits in the 3 years I owned the car. Fond memories of the STI, for sure. I then traded it in on an ‘06 Evo IX MR, the Subie’s arch rival. I got a great residual value on the Evo deal, with the STI being unmodified, even after disclosing it was track driven.
Below a photo of me and my oldest son in the STI at Pocono East in July of 2005. I was giving him all my speed secrets id learned. In my mind’s eye, I can still see that hood scoop wiggling about as it was driven hard.