2021 Edit:
FFmpeg has added support for LEGO Racers' tun and pcm files as of version 4.4.
I advise everyone to use that instead of this program as this program isn't 100% correct.
Thanks to mumboking for bringing this to my attention.
Original post:
Although I had already posted my ima2tun program >here, I've decided that a separate topic might be more easy to find.
This zip file contains my ima2tun program tunconverter, SoX, and some handy-dandy batch file