Digital BW, The Print

After Steve Kale's post I tried, out of curiosity, printing a 100 step gray scale from an Epson 4000 onto Kirkland paper and measured on an X-Rite 810 and found the following Dmax:  
                     
           Epson driver - 1.96
           QTR matte ink - 1.84
           QTR photo ink - 1.51

I was really surprised at the QTR results. Any comment?

Ian