okay, a 400K limit for the song you produce - that’s a fair challenge, I can dig that
but what’s with the shoddy quality of the samplepack you provide? if you have to molester the poor innocent samples with an MP3 encoder, at least use 192, or at the very very very least, 160 kbit - the high end in these samples is already mashed-out and mangled, which won’t exactly make it easy to come up with a great track.
have you actually tried pitching 128 kbit MP3 files up and down? the audible artififacts, especially on the high end, become painfully obvious - just compare to the original samples … with 160 kbit this already improves a lot …
would an extra 100 KB on the samplepack zip really kill your server?