Originally Posted by Provocateur

A coated pipe is going to be cheaper than a stainless steel one because it is just mild steel underneath the coating. Once that coating comes off, it will begin to oxidize. 304 stainless should never rust, in theory, and will last longer than you will have the car.

Apex'i doesn't make fully stainless exhausts but Greddy and Skunk2 do. Like I said earlier, stick with fully 304 stainless, an exhaust diameter around 60mm, and a sufficient muffler and you'll be happy with it.