When you install the 4 into 4's Steve, add a cap full of two stroke oil through your gas tank every few fills, it won't blow much smoke, but the two stroke oil will be "fogged" through your pipes, and this will slow down the the rusting process.
Seriously, mine had 5000 miles on the odometer when I bought it, and the pipes were rotten. It's the chroming procedure that kills 'em, a lot of the acids and salts are trapped inside the pipes once they're done, and as soon as they get moisture inside them again, the rusting starts. Blow a fine mist of oil thru 'em, and they'll last a lot longer.
Or, if you intend to show it, install a Kerker and just put the OEM pipes on for shows. Cheers, Terry.