Hello KurohaBecher. I found the graphics with
Lunar Compress.
Put "decomp.exe", "recomp.exe", "Lunar Compress.dll", and "Super Mario Kart (US).sfc" into a folder. The Mario Kart ROM must be 524,288 bytes in size (no header)
Using Windows, hold the shift key and right click inside the folder, select "open command window here". Use the command line:
decomp "Super Mario Kart (US).sfc" graphics.bin 71996 4 0
Change the "graphics.bin" file using a
graphics editor, then insert into the ROM:
recomp graphics.bin "Super Mario Kart (US).sfc" 71996 4 0
Use "sniff.exe" to find other locations like 70000, 70B29
You might want to change the colors and map data which is more work
