This is the expanded Windows version of ProStreet's score and the extra tracks fill in gaps the console release left. Junkie XL's "Interactive Score" is fascinating because you can hear how the layers were meant to shift in real time during gameplay.
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"Post Race" and "Main Menu" add context you don't get from the racing tracks alone, quieter and more reflective. "Brake Pipe and Hose" fits right into the automotive naming scheme with more of that grinding industrial sound.
The "327 V8" variant here is credited directly to Junkie XL and hits with slightly different mixing. Having "Soundtrack 2" as a catch-all piece rounds things out. If you played ProStreet on PC, this is the fuller picture of what Junkie XL built for those races.