MAX Cheat Zone

Gran Turismo 3: A-Spec

Pro difficulty level:
In the select difficulty level screen, point the cursor on 'Difficulty' and push L1 + R1. Do so, and you get the Pro difficulty level.

Make the more difficult non limited races a breeze:
Save money and as soon as you are able to purchase a powerful turbo car like the SKYLINE do so. Then buy upgrades as you can. Once fully upgraded race the Superspeedway endurance race as many times as it takes for you to win the Formula One race car. It's acceleration and handling are bested only by a couple other F1 cars which you can now win with ease.

Cheap HP upgrade:
When you get a new car, before racing it take it to the GT shop for an oil change. If the car has over 400 hp you will usually see about an extra 30 horse.

F687/s:
Successfully complete the 100 mile Seattle Circuit Endurance Race