I have no idea about a jetpack, but these are valid codes. Bring up the phone so that you can enter a phone number. Enter accordingly:
Spawn Police Helicopter: 3595550100
Max health and armor: 4825550100
Different weather: 4685550100
Spawn Boat: 9385550100
WARNING: Police will chase you with 5 star equipment if you boat out too far!
Spawn Car: 2275550175
Spawn Motorcycle: 6255550150
A special surprise: 2675550150
Have fun with the game! Note: Using codes may temporarily block achievements. Codes not tested on xbox live.
Spawn Police Helicopter: 3595550100
Max health and armor: 4825550100
Different weather: 4685550100
Spawn Boat: 9385550100
WARNING: Police will chase you with 5 star equipment if you boat out too far!
Spawn Car: 2275550175
Spawn Motorcycle: 6255550150
A special surprise: 2675550150
Have fun with the game! Note: Using codes may temporarily block achievements. Codes not tested on xbox live.