Alright, make sure your your computer and ps2 were turned off when you connected it. Next turn on you computer and let the beging load, put in the computer cd and finish loading. Turn on your ps2 and put in the ps2 disc. wait untill everything finishes loading. On the lower left is a button marked "Memory Card" go in let everything load, then choose you game save and click back up. Go into "PC Database" on the lower middle part. Click your gamesave and choose send file and put it in a file where you can locate it.
Open mk program and choose "read garage" gointo the file where the gamesave is. from there you can edit.
afterwards choose write garage and either write over, and create a new gamesave. go into X-port thing and choose import file. import you new file and chose just that file in pc database.
Now if you have switched to a different game, you will want to turn it off, and then turn it back on with the X-port dsic. now having you gamesave choosen on the upper left hand side, choose restore, and then let it load. it will ask to overwrite, choose yes. from here put in your GT3 gamedisc let it load and see if the hybrids work.