to resync voice with the game just replace the US intro by the japanese one. it's the DAT file named bg or bgm, can't remember wich one i tried.
i replaced
- msgvo.dat
- msgvo.dat.tbl
- bg.dat or bgm.dat
works fine...for now enjoy
Not sure about other models of Pi4 but the Pi 4 B with 8GBs OCed to 2Ghz handles PSP really great except like 1 game I found and it is playable it just looks bad lol Motor Storm Arctic something or other.