from my experience, and my testing 99% of the time, 16x will yield the best results. Now on some really good media, oyou WILL get lower C1/C2 errors at some faster speeds However I would never push faater then 40x...I think Yamaha was onto something when they stopped producing drives at the 44x mark.
After having read the jitter testing done at CDRinfo.com, I have to seriously consider burning faster then 24x to be a really bad idea for playback on some systems. Generally speaking, if you burn a CD-R faster then 24x, you wil usually end up with a CD-R that has higher jitter errors then allowed by CD standards. This is not something I want, and I believe it is likely to cause problems with compatability with some players.
with 99min CD-Rs, I will never burn them at ANY other speed then 12x or 16x. I did some testing of my Ritek 99min CD-Rs, and I tested all the burn speeds from 4x to 48x with at least one CD-R each (though in a couple cases more then one) and there was a VERY deffinate quality curve. The quality peaks very deffintaly right at 12x and 16x, and has a significant raise at 8x. Don't even think about 4x or 24x, and you probably won't be able to read the disc if you burn it at 32x, due to the incredibly high C1/C2 errors.
Of course some drives can only overburn properly at the lower speeds, so this kiinda leaves you in a ight spot!
Punch Cards -> Paper Tape -> Tape Drive -> 8" Floppy Diskette -> 5 1/4" Floppy Diskette -> 3 1/2" "Flippy" Diskette -> CD-R -> DVD±R -> BD-R
The Progression of Computer Media