After seeing all the bad feedback regarding Princo on this and other sites I have kept well clear for a while, and used Ritek G04 4X -R Grade A, Memorex DVD+R 4X (CMC), TDK DVD-R 2X (MXL), and Maxell DVD+R (Ricoh I think), philips DVD+R (CMC).
Anyway I run k-probe all discs I have made and to date best results were with the TDK DVD-R 2x (MXL). Now I try the cheapest datawrite yellow top (PRINCO), which is quite a good looking disc and the error rate is by far the lowest!! I thought these discs were supposed to be rubbish!?
Burner is LG GSA-4040B.