ok, I seem to have made an improvement.

I read on the NEC website that drives shouldn't be flashed if you have Intel Ultra ATA Storage Controllers installed. it says to remove them in add/remove programs. well actually they show up in device manager and removing them requires restarting your pc, which just means they are redected.

So I tried making a boot disk and flashing firmware from DOS. It seems to have worked. 4571A speeds are back up again, and 2510A seems improved, although not as fast as its younger brother. Just ripped a 7.5gb disk in 18.5 mins - average 4.9x, max 7x.

Is that good, or could I hope for better speeds?