Media recommendations for Liteon LH-20A1S?

My 20X DVD burner seems to be topping out at 16X and I’ve tried several brands of media without much luck.

I’m using the drive exclusively for data backup, so fast reliable burns are what I’m wanting without waiting 7 to 8 minutes.

I’m currently going through a spindle of Verbatim DVD+R 16X, SmartBurn tells me they are made by Mitsubishi.

Before that I was using TDK DVD+R 16X media. SmartBurns says they are made by CMC Magnetics Corp.

And I first tried Sony DVD+R 16X media, made by Sony. Actually these I think I was getting 18X out of and SmartBurns says they will do 18X. So I might go back to these if I can’t find something that will burn at 20X.

So was just wondering if there is any media that will burn at 20X? Also forgive the dumb question, but why is there no official 20X media considering 20X drives are common place?