Header Q's

Why are boxster headers so expensive compared to 911 headers??? I see on ebay all the time 911 headers for 200 bucks, etc..., while boxster headers are going to 600+. Same header just backwards flange. So if I buy some 911 headers can I cut off the flange and have them welded back on but turned around? I saw an auction today for 911 headers sell at 120 bucks (these right here, http://cgi.ebay.com/ebaymotors/New-99-07-Porsche-996-911-997-GT3-SUS304-Race-Headers_W0QQcmdZViewItemQQhashZitem180154551711QQi temZ180154551711 )

So even if it cost 200 bucks for some joe schmoe to weld 6 pipes you would be ahead. Any experts wanna say the feasibility of this?