In addition, when you read the upgrade document, they have conflicting information, all in one paragraph! First they say you can only use PS/3 Steam Upgrade files, and then in the next couple of sentences, they talk bout using PS/2 sound files! The truth lies somewhere between those.
Finally, when using some PS/2 upgrade files, there is a special chain file that you have to load in order to restore the missing chuffs, that's another thing that's not mentioned anywhere. 
While it's fashionable to assume all will go smoothly, ask anyone that's been doing a lot of these upgrades, and the story will not be all smooth sailing.
