Cheats for Forza Motorsport 4 on Xbox 360.
Note: This game is also referred to as FM4.
For cars that are not naturally aspirated when stock, and that have aspiration conversions, you can remove the stock turbo/supercharger using this glitch.
Purchase one of the aspiration conversions, then install the race version of it and uninstall it. Uninstalling the race version will not add the stock aspiration back to the car, resulting in a PI rating that is lower than stock. This can be helpful to move cars down a class or to reduce the PI to allow for more upgrades in the current class.
Freely drive in the pits:
To freely drive in the pits (good for photo mode), you will need to start a test drive from the tuning menu. Drive into the pits until the computer takes control of your car. Pause the game, change something in the tune and apply it (the change must be applied, not just saved or cancelled). When you resume the game you will have full control of the car and be able to freely drive around in the pits.