I'd go for a K&N Typhoon and a header from speedlab. Just a shorty intake alone will not give you appreciable power... not so you can notice.

The two biggest power-gainers you can put on a vehicle are the Unichip (or a similar aftermarket chip) and an aftermarket exhaust manifold. Drop-in air-filters, your typical shorty Intakes and mufflers make the car feel a tiny bit peppier, but that amount of power is barely noticeable in daily driving.