This hack replaces most of the menu music with the one from the Japanese version.
Unfortunately, due to the way the music data is structured in the game, it wasn't possible to replace the race music. Sorry. On the other hand, this hack has kind of a GT2 vibe to it, in that the menu music in that game wasn't replaced for the Western version, only the race music was.
Two download links are available for the USA version: one with the Simulation Mode music from the International version and one with the Simulation Mode music from the Japanese version. This is because replacing that music from the one from the Japanese version causes the sound effects not to be properly mapped in the Simulation Mode menu, so not only do they not play correctly, but every time the game tries to play them, the music can get messed up. Also, the game will crash when attempting to enter Simulation Mode on real hardware. At this time, fixing this is not possible.
The author is not going to replace that music in the European version because of this issue, and because it's very fiddly to do in that version.
NOTE: Jason Page did a wonderful job when he made the menu music for the Western version. This hack is only intended to offer a choice to the players.
==USA version download links:==
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https://www.mediafire.com/file/7ob75uceqzt05fb/Gran+Turismo+Japanese+Menu+Music+to+USA+Version.zip/file - Simulation Mode music from Western version
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https://www.mediafire.com/file/0nb5uq5vbwz03wn/Gran_Turismo_Japanese_Menu_Music_to_USA_Version_%2528glitchy%2529.zip/file - Simulation Mode music from Japanese version, glitchy sound effects
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https://www.mediafire.com/file/4gsp6psfj8z8ozv/Gran+Turismo+Japanese+Menu+Music+to+European+Version+(EDC).zip/file - European version download link (for the EDC version)
Gran Turismo (v1.1).bin
SCUS-94194
CRC-32: 2B3845AA