but u can flash any firmware for Lumia 800 by this toolNokia Care Suite 5.0
Because once changed, updates via Zune are avaible...Why do you want change product code?
If it's for unbranding your phone, you can flash a country variant firmware without changing product code...
WHat is the "connecting/deconnecting method" ?I managed to force the update by the connecting/deconnecting method even with an unbraded fw with the orange fw product code unchanged. So it's possible to update the fw.