Save the money on the DP and get something cheaper like the CNT. You can get the catless version for around $200.
Exhaust wise I've only heard a few, the Invidia Q300 is really loud on the hatchs. Downpipe wise the Invidia Bellmouth is a great downpipe for the money.
Probably a little over $2,000. I really like the look of the Greddy exhaust and the downpipe will provide the real power.
You don't need to spend that much on a turbo back, should be able to get the any bell mouth and the greddy catback, AP and tune for about $2k Sent from my T-Mobile G2 using Tapatalk