Also from what i gather cams wont give you more than 10-15 HP and you will sacrifice some of the smoothness (rough idle especially)

 

The best bang for your buck with the 4.2 V8 cars is a cat-back exhaust. The downpipes are expenisve and provide marginal power increases at best. In some cases the midrange power drops off on the dyno. The Fast Intentions and the Labree setups are the best systems for the money. Milltek is very nice, but very pricey.