Underground CD Volume 3.3 Codes -

View R-Type Delta codes:
Hold L1 + L2 + R1 + R2 and press Triangle at the main menu of Disc 1.

View 3Xtreme information:
Press L2, L1, R1, R2 at the main menu of Disc 2.

View Syphon Filter information:
Press L2, R2, R1, L2 at the main menu of Disc 2.

Toggle background music:
Press Start at the main menu of Disc 1, then press Left or Right. Press X to return to the menu.