What are some good parts to make a 97 intrepid sound better, and to go faster?

There are not a whole lot of performance parts or aftermarket parts to make a 97 go faster or sound better. You can install a CAT Back dual exhaust on the car. That sounds much better. You can always install a Drop in K&N air filter. Other than that you are looking at installing the usual Spoiler, Tints, Headlight covers, underbody neons, Rims, ... so on and so on. Check out http://www.dodgeintrepid.net for everything about the Dodge Intrepid.