Youd have less of a problem doing the physical swap than you would convincing the dealer to do it. They typically wont make a switch like that so as to not break up a special option package from one car to another. Remember if that 325 doesnt have 16s then they are probably an upgrade, and if no one likes the ones from the XI then they will have a harder time selling the other car too. If they are both simply base wheels and not part of an option package (sport,touring etc.) then they might do it for you.
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<img src='http://members.cox.net/inelson5/wooani.gif' border='0' alt='user posted image' /> The whistles go WOOOO!!! *BUBB RUBB FAN CLUB*