Here are some leaderboards for track times if anyone is interested

For Cyberscore you need to submit using a Gameboy, Gameboy Player or DS since emulators isn't allowed. Picture proof is enough:
https://www.cyberscore.me.uk/game/1813

Retroachievements uses its own emulator where it keeps track of records and achievements in the game:
http://retroachievements.org/Game/5127

Just as an addition, since we don't host Time Trials on here but would like to have all the known leaderboards in the forums for all other people:
The Cyberscore link is the English leaderboard. The Japanese has its own leaderboards however:

Japanese (Time Trial times): http://crashhouse.curahome.net/crashtime/?game=nc_gba_timetrial
Japanese (Trophy times): http://crashhouse.curahome.net/crashtime/?game=nc_gba_timetrophy

As of a few weeks ago, Time Trials for individual levels are also hosted on this site here for both the GBA and the N-Gage versions.