The scan is generally excellent.
PI Errors (top graph) less than 8 are close to the best you can get and are an indication that your burner is performing nearly perfectly. However, the most important numbers are the PI Failures (bottom graph). The PI Failures graph was very good until near the end of the burn where it spiked to 15. This is what caused your quality score to drop to 91%, since CDSpeed bases this score almost totally on the peaks of the PI Failures. For comparison, a spike to 8 would produce a quality score of 95% which is what you were working on until that high spike at the end. You can rerun the scan again to see this in action.
This trailing PI Failures spike is probably nothing to worry about, although if you were to reduce your burn speed from 16X to 12X those trailing spikes might vanish. In any case, it's still in the green area (the area below 16 is the green "safe" area). There's no indication of a ramp up of errors near the end of the burn, which often happens in a marginal burn, there's just a couple of spikes near the end. Combine this with the fact that your PI Errors were nearly perfect and you get a big:
:iagree: Congratulations on a great burn :iagree: !
Only one other suggestion. CDSpeed is a bit hard to read when you leave it configured with its default "Legacy" colors. My above comment "in the green" would make more sense if you take a moment and reconfigure the CDSpeed color scheme as follows:
Click menu item File->Options and select the Disc Quality tab along the left. In the Colors section near the bottom, find the pulldown box marked as Theme: and switch it from "Legacy" to "Bright". Click OK and then run the disc quality test again to properly see this "green" area (and the light-red marginal area just above it).