You definately want aluminumized pipe. It doesn't rust. The aluminum coating also makes the pipes look like new longer.
When you look at the pipe, ask to see some with and without the coating so you can see the difference. They usually charge more for the aluminumized pipe, so pretend you don't know the difference and act dumb. Steel pipe is a darker silver, almost blue. Aluminum is brighter, more like a true silver. Also, they tend to put a heavy coating of oil on steel pipe so it won't rust until they put it on your car.
FYI, my aluminumized exhaust is 6 years old and still looks good. the aluminum coating does get scratched from road debris, so you'll get little rust spots here and there.
Hugger Orange & white 69 Camaro with supercharged 350, Tremec TKO, and 3.73 12-bolt
[This message has been edited by gheatly (edited 03-07-2000).]