Like I just said, you can only get 6-16x reading speed with pressed DVD-ROM Single Layer media - not with any burned DVD media and not with DVD-ROM Dual Layer.
If you want/need 16x reading speed with burned media, you should get another DVD-ROM or DVD-RW drive, e.g. BenQ DW1650/1655 or LiteOn(*) or NEC drive. Other recent drives may also be capable of 16x reading of burned media.
(*) Some LiteOn DVD burners only read at 16x for 16x certified media but read other DVD media at 12x.