Default Q700S kitchen question

hi guys i m in a little trouble i get su and busy permission error if i cook a rom in kitchen as far as i searched i got this
QUESTION: I get busybox errors during flashing; e.g. "Can't chown/mod /system/xbin/busybox (No such file or directory)" or "E:Can't symlink busybox ..."

Apparently you need to upgrade your SPL, and it has nothing to do with the kitchen:
can someone explain me wat that SPL means and how to i update it ???