My 3500 does 40X on amost anything I have put in there, except on some of those black PNY CDRs (24x), and on Verbatim CDRs it does 48X. I have 100 TY blanks waiting to, but I havent tried them yet.
When I burn DVDs, it's kind of touchy. Before I updated the firmware a while back, it would burn my Ritek DVD+Rs at 8x, now it's 4x, but some Verbatims that were 4x now burn at 8X, and the three Fujis I had left, that burned at 8X before, burned at 16. Some mystery brand ones a friend gave never worked period, but now they ALMOST finish before they are announced as coasters. Before the update, It was an instant coaster as soon as the burn started.