the most bang for buck mod you can do is a remap. Even on an otherwise completely standard car it makes a fair difference.
Use a tuner that knows these cars well, rather than a generic flash tuner that hasnt a clue what they're doing. You dont say where your located? I get a sense your from the US, so recommendations here are likely going to be thin on the ground as its a predominantly UK forum.
The remap alone will take it to a little above 300, but it really depends how far you want to go. With decent downpipes and exhaust, and some intercoolers, and a good tune, you'll likely see 340-350ish but you wont get much further on the stock turbos.
Dont bother with a CAI, the stock airbox is fine until your going for BIG power.