Trolling on ebay I found this. It could be used to replace that very small non-efficient heat exchanger that comes with the Paxton, and for $150 its a deal.
http://cgi.ebay.com/ebaymotors/Alum...emQQcategoryZ33742QQihZ002QQitemZ120206119483
http://cgi.ebay.com/ebaymotors/Alum...emQQcategoryZ33742QQihZ002QQitemZ120206119483