We cant still unlock GT6 saves
Bruteforce it, take a GT6 save you already have, back it up twice and work with one of the copies, extract the account_id, user_id and PSID and replace them in the save you want to make work with your main account, blank the save to work in any account, decrypt all files and then replace the info, re-encrypt files and then rebuild.
The game will detect the save as "yours", you can have all the money and stuff, but you wont get online working because game ID *the name you have to put as a player in-game* is related to your PSN account, so no match means no work, no work means error, saying to log in, Even if you're actually logged in, it wont detect the status of the actual account/name registration that's encoded into the save
*Already tried it by myself* LOL still cant figure out a way to change the player id in-game, because i really couldnt find anything else in the way of reading the save, PS i didnt got "another player's save" message