All guns:
Press Start to pause game play and highlight the "Map" option. Then, press 
Triangle, X,X, Triangle, Square, Circle, Circle, Square, X, Square, Circle, Triangle. 
The sound of an engine will confirm correct code entry.

Exit the RIOT mode:
If you are getting beat up by the swarm of cops that come out in full RIOT, go to 
the garage and park. The RIOT will be turned off. To save your progress, you will 
have to pull into the garage again.

Other towns:
When you progress enough, you will be taken to another city by following the "M" 
on the map. You can actually go back to the previous city at anytime. Pay 
attention where the exits are for the cities.

Easy kills:
If a gang of cops or rival gangs are coming after you, learn to drive and shoot in 
reverse. Back away from the cars that are about to explode or the explosion will 
take off a tremendous amount of armor.

Easy money:
Listen for the weather report on the radio. When you hear the report for the 
tornado warning, find the tornado and follow it from about a block back. You can 
pick up all the scavenger parts from the vehicles that the tornado destroys. For 
extra cash, try to induce a RIOT near the tornado. The increased traffic and 
constant stream of cops will give the tornado more toys to toss around and give 
you more cash.

Faster upgrades:
Stay by your garage and induce a RIOT by killing the civilians and other gangs on 
the street. To get the RIOT factor up faster, blast away the street cops. When your 
armor is running low, drop by the garage and pick up a repair kit. Keep repeating 
this until you get enough money for the upgrades. If you "fail" the RIOT, do not 
restart by loading the previous save. This allows you keep all the money, no game 
penalties will be levied, and you will keep all of your upgrades. The only thing you 
will lose are all of your weapons.