SCSI drives have amazing data read and write capabilities, this is usually because of the fact that the drives run at around 10,000 RPM as compared to around 7,200 of an IDE or SATA drive. It was predicted that with the advent of UDMA 100, and above, that SCSI would would become obsolete. I don't see them so often in home computers any more but i still come across a lot the workplace, in my opinion they out-perform SATA drives hands down. It's probably a combination of both high speed cable and SCSI drives that give your friend his amazing speeds though
What's his connection speed?