Linearising matte paper - best practice - what Dmax?

Piezography Professional Tools
1

Hi Walker

I have just reprofiled IFA11 and Museo Portfolio Rag based on the Hn PhotoRag quad. I am getting a Dmax of 1.58 or 1.60.
This is not very high. Can this be due to the PhotoRag quad. Which quad would you recommend?
Thanks, Markus