Wow this thread went downhill fast but managed to mature pretty quickly...
Some good advice posted so far and I agree with most of it. The 86 is still a new platform (and a brand new engine that's different than previous Subaru engines in almost every way). So yeah, there's little data on REAL longevity of engines with forced induction, or how long the rest of the drivetrain will last after dealing with 50%, 100%, or even 300% power over stock. There is no easy answer to satisfy everyone who wants "more power" because it's a very vague definition.
Secondly, bigger wheels will most likely make the car slower. It's small and lightweight, and adding rotation weight like bigger wheels makes a noticable difference. Stick with 17's for performance, or go with 18's for looks. I personally think 19's on this car is a terrible idea, heavy, and they look just too big.
The car wasn't built for straight line speed, it was built to be a driver's car. If you've never been to a real race course, it's something you should DEFINITELY sign up for this summer. Find a track event that includes driving instruction and go with a humble head, ready to learn. You'll have so much fun that it might make you look at the car in a completely different light. There's something to be said for really knowing how to properly drive fast in a slow car.
I'd recommend in the mean time, to look for little upgrades here and there that you can try to do yourself that will improve the driving experience overall, such as better brake pads, stainless brake lines, brake master cylinder brace, maybe some exhaust for a different sound, wheels, tires, springs, coilovers, bushings, swaybars, etc can all make the car feel different and more responsive and communicative, allowing you to simply have more fun. How about learning new techniques? such as rev matching your downshifts, or double clutching? (I know DC'ing isn't necessary, but it's fun).
As someone advised, check other people's build threads and see what they've done. This will help give you a better idea of exactly what suits your specific needs because many owners explain why they made certain choices and what difficulties they ran into. Keep in mind, if you're having a shop do the work for you, this is good for technical reasons, but labor could get expensive, quickly.