Complete the various side missions scattered through Vice City to unlock new things.

Effect - Code

Armor Boost - Beat all 15 levels of the "Vigilante" side mission
Become Fireproof - Beat all 15 levels of the "Firefighter" side mission
Free Pay N Spray - Deliver all 32 cars to the Impound Yard
Health Boost - Beat all 15 levels of the "Air Ambulance" side mission
Infinite Sprinting - Beat all 15 levels of the "Paramedic" side mission
Infinite Swimming Strength - Beat all 15 levels of the "Beach Patrol" side mission