What options did you chose in the kitchen? Kernels can just be replaced overwriting the one thats already there (not sure if anyone has a download of the stock kernel available but the custom ones are better anyways.) Any stock apps/boot logos/animations that you replaced are backed up to the sdcard and its just a matter of copy/paste the files back to their original location (except for the stock apps which if you wanted to put back where they were would have to have root access, a shell terminal to remount the /system/app/ folder as rewritable and paste the apks there then run them with a file manager). My advice to you would be flash the stock de03 with custom recovery -
Login - via the sprint updater. This will return everything to stock and with the custom recovery already installed you can back /system and /data. This way if you flash something you dont like you can just restore the backups (/system will backup the stock apps /data is market apps, user settings, etc). The only exception here is the kernel but they are easy enough to replace. Hope this helps
P.S. - Just took a look over at the kitchen as i havent been there since they updated it last. It appears they have added options to replace
some of the stock items back to the phone, just chose those you wish to restore and create the .zip.