a PPP upgrade for the the hatch that created the 330s was effectively a prodrive back box, filter and remap
for a full system check out Milltek
http://www.millteksport.com/exhaust.products.cfm?variantid=283
for a car this new I if you just want the backbox go for a bolt on option - less hassle and you can fit it yourself on your drive. The Prodrive one I had on mine was great quality
depends on how much you want to spend??