Is the ND-6500A read speed locked for non-video DVD discs?

I’m the process of testing an NEC ND-6500A notebook computer drive which was sent as a replacement for a Sony drive that was having problems recognizing previously burned media.

My drive firmware is stock 202C. Because this is a replacement drive, I don’t want to start testing different firmware before I confirm that the drive is performing properly (in case I have to send this back for a second replacement).

From what I’ve read, the stock 6500A is rip speed locked for DVD video discs (with a VIDEO_TS folder in the root), but I’m also getting slow read speeds on burned data discs.

The following is a Read Speed test for TYG02 8x DVD-R data disc burned at 4x on the 6500A. The average read speed is 2.05x. This graph looks exactly the same as a Read Speed test for a DVD-video disc burned on the same media.

When I do a Read Speed test on this same disc in my desktop ND-2500A drive I get a smooth upward curve starting at 3.5x, ending near 8x with a 5.5x average speed. Also, the original Sony notebook drive had the same smooth, upward read speed curve, with an average of 5.5x. I’ve double checked that my IDE Channel is in Ultra DMA 2 Mode, so I don’t think there are any hardware issues aside from the NEC drive itself.

Is this 2x limited read performance normal on a burned data DVD-R with stock firmware? Or do I have a faulty drive? Will firmware with the rip speed unlocked fix read speed on all discs, including data discs, or just on DVD-video discs?

Thanks for your help.