Go to the options screen and set Vibration to 1, sound effects to 0, music to 0. Now hold L2+L1+R2+R1+ circle + square.
Get Maniac Difficulty & Extra Helicopters:
Finish the game on hard difficulty setting for maniac difficulty and a new helocopter is yours. Finish on maniac for another new one.
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GameShark Codes
[M] Must Be On
EC8782801449D2E4
Inf Ammo Weapon 1
4CD5B2481456E788
Inf Ammo Weapon 2
4CD5B24C1456E788
Inf Ammo Weapon 3
4CD5B2501456E788
Inf Armor
4CC1D49A1456248F
Never Overheat
4CC1D48C1456E7A5