In my opinion, the typical 'stage 2' setup of a downpipe, catback, and tune is best for the money. 25% power increase for roughly $2000 total. That's not bad at all. And that's with name brand parts. Throw in the Cobb SF intake if you like too... assuming you're going with the Cobb AP.
That's approximately 330HP crank give or take. You're up to around 265 to the wheels. (In general, stage 2 upgrades take your stock crank HP and make it your new wheel HP... with different tunes, results will vary.)