Oh, I'll also email your original DVD rom bios & hardware keys back to you. (In the event you ever wanted to try to reflash or return to stock)

Informational ...
The 360 has a chain of hardware signatures. The DVD rom has a unique key that the motherboard is looking for. If you were to take any spare 360 DVD rom from eBay and pop it into your machine, it wouldn't work. They DVD key wouldn't match.

The flashing process includes the extraction of DVD key from the drive, and the rewriting of the key with the custom firmware.