A CAT back is going to be the best option as it is only a 1.8. Replacing the CAT will not do anything apart from costing alot of money. If you're really keen on a "performance" system, make sure they use Mandrel bent pipes as opposed to press bent pipes to reduce exhaust flow restiction thru the bends in your exhaust. 304SS is the goods and i'd say the exhaust will outlive the car but thats not a bad thing when you have a sweet Italian 4-pot singing away with a raspy gurgle coming from the back.
