Unlockable Weapons
When you have reached the required Rank the following weapons can be bought at the armory in the precinct.

Unlock 5.56mm Carbine, 7.62 Auto Sniper, FlashBang:
Rank 1 Detective

Unlock .45 Special, Tactical Shotgun, 5.56mm Bullpup AR, Sledge Hammer:
Rank 2 Detective

Unlock 4.6mm PDW, 5.56 Assault Rifle, Tranquilizer, Stunt Baton:
Rank 3 Detective

Unlock Stun Gun, 9mm SMG, Standard Shotgun:
Rank 4 Detective

Unlock .45 ACP, Beanbag Shotgun, Caltrops, Flashlight:
Rank 5 Detective


Vehicles
When you have reached the required Rank the following vehicles can be bought at the garage in the precinct.

Unlock 6.5L V8 Custom SUV:
Rank 1 Detective

Unlock 5.4L SC V8 Coupe:
Rank 2 Detective

Unlock 2.5L L4 Sedan:
Rank 3 Detective

Unlock 6.0L V8 Coupe:
Rank 4 Detective

Unlock 3.5L V6 Sedan:
Rank 5 Detective

While you are on the CompStat/Map screen hold down the shoulder buttons before entering the following codes

Ultra Easy Mode: B, X, A, A, Y and B

Unlimited Endurance: B, X, A, X, A and B

Double Damage: A, A, X, A, A and A

Unlimited Ammo: B, X, A, X, X and Y

Get a Million Dollars: X, X, Y, X, Y and X

Super Cop: Y, A, Y, A, Y and Y

Unlock Redman Gone Wild Mini Game: Y, A, A, X, A and X

Unlock Redman Gone Wild Mini Game: Complete the Game 100%

Puma Shoes Outfit: Collect all 10 pairs of Puma Shoes