up/downpipe, catback... excellent.

I'd hold off on an intake though. The stock airbox will work well even past 300hp. Do remove the silencer though, and you can hack it up or get an elbow or even do what I did and stick a velocity stack into the fender. That'll eliminate some restriction, you'll hear the turbo better, and its basically a "free" mod depending on how you go about it.

Since you have a wagon, a bigger rear sway (a stock wrx bar would even help, I have one off my 04 if you want it... free!) would help your handling too. Not sure if you're going that direction, but you did mention better springs/struts. You also don't say which strut tower brace you got, but a rear brace really does help for a wagon. They even make quick-release versions so you can remove the center bar if you need to stick something back there.