I have a LiteOn 48125S in an external firewire case, I burn at 48x all the time in Toast and in the finder/iPhoto backups. iTunes limits Audio burns to 24 or 32x, but with data, the sky's the limit. This is on a QS DP800, 10.3.1. It's burned at full speed since I got it back in the 10.2 days. Oxford 911 chip in the generic external case too....