Prefetching the DDS BC7 pack requires 4.6 GB RAM. Supported Mario Kart 64 versions: NTSC-U (PAL and NTSC-J should work too).
Newer versions of WinRAR should work too. You might need to download 7-zip to unpack them. Both packs are packed in the 7-zip format. Both the PNG and DDS pack are uploaded. This new updated pack which got ported by GhostlyDark for the Wii VC replaces the old pack I once made. That pack is still WIP and further progress will be synced with this Dolphin port. The pack has been revamped with the textures of Andrat's Mario Kart 64 HD for GLideN64.