My opinion Do NOT paint those wheels. I think the silver BBS rims look absolutely flawless/or PRISTINE on a black STI.
You need some type of Contrast, for the car really to scream BAM. Ya know?

Get a sweet set of summer tires and spend the other k on savings or suspension mods?

Sticky tires
The Eagle F1's are way better than the Kumho's, but also more expensive, but they're nowhere near the dry performance (or wet, for that matter) of tires like the the BS RE01R, the Dunlop Dirreza Z1 [Star Specs], or the Azenis RT615, The Azenis can get shitty in water.
Their are a a few of us that run those tires here... Byron , Dan, myself.. They are a good Autocross tire. .I saw a good second and a half overal improvement in my times with the 615's
THe Hankook Z212 fall between the Eagles and the others. FWIW, I tried to use the Eagle F1's in standing water and heavy slippery conditions and super stickies in non-hydroplaning conditions So at slower speed wet play, the stickier Street Tire legal tires (the RE0R, Z1's and RT615's) are likely to be better wet, as well as dry performers. The trade off is wear vs price..
700 bought retail on internetz . Or clearance on others.. Those are summer tires I would play with.. ATM..
I would speculate you would want a 225/45/17?
Marty