Performance: Header for midrange. Stock exhaust OK, 60mm better. Comptech Icebox is nice on the midrange and won't suck up water like a conventional cold air intake.
Handling: You'd be amazed how well these cars can handle. You can upsize the rear sway bar to an ITR bar to eliminate that push. 205 tires. Springs and shocks can make a huge difference if you're willing to toss a bit of money at it.