Cheat originally made by asasega. I ported it to more game versions and expanded it with more features.
An improved 60 FPS cheat. I expanded it to re-enable tire smoke effects and the rear view mirror, originally disabled for performance reasons when running the game in Hi-Fi mode.
WARNING: When this cheat is in use, existing replays will break.
Simulation timescale in Arcade
American and European versions of Gran Turismo have a weird difference to the original Japanese release – in those Arcade Mode is noticeably faster than the Simulation mode. I investigated it and found that in these versions, Arcade Mode runs at 125% speed, although naturally without speeding up the in-game timer. With this code, Arcade Mode is restored to 100% speed, just like in the Japanese version of GT1.
A clip from Submaniac93 illustrating the differences well: