Better performance for a 02 impala

Getting a 02 impala with a 3.8, what some more power and better gas mileage, what should I do? I was thinking k&N cold air intake, an exhaust, and pulley. Was also wondering what kind of exhaust to get. I looked at dynomax and they make a 04-05 super turbo kit for the ss impala, and I would think that would fit but am not totally sure or if there is any better exhaust that is cheaper, that sounds better and I could put together would be nice too, would like duals too. Is a new pulley a good idea too and how about a hypertech programmer? Anything else you can think of I would really appreciate it.