Sat Pro 4600 and SD-R2002 read speed

Archived from groups: comp.sys.laptops,japan.comp.toshiba (More info?)

The specs for the CD/DVD combo drive (Toshiba SD-R2002) on this model are
CD/DVD read speeds of 6X/24X, and CD write speed of 4X.

I am unable to get more that 2X DVD read speed out of this thing using DVD
data discs (forget about video ripping). Trying Nero DriveSpeed to detect
its capabilities I only get 2X; if I manually add 6X to the list and try
to select it, no speed improvement is seen.

Are the specs for this drive mis-stated, or is there something else I've
missed? Is there a better utility for detecting/adjusting read speed?
Yes, DMA _is_ on.