Tensioning Dynex rig

[seacap]

Hi all,
I have had a rig built with Dynex Dux for the last 4 years. One of the questions has always been how tight to set it up.
I did as I have always done. Taken the boat out sailing and tension until the shrouds no longer goes slack on the leeward side.
I now see that Colligo Marine has issued a modified guide for using the Loos PT-3 gauge. On the chart for 7mm they list 6 on the gauge as being equal to a 650lb load. My rig is tight, no slack on the leeward sailing side. But it measures only 2 on the Loos gauge.
Is this because of the stretch of the Dynex being lower than wire? I'm I just not tight enough? Why would I want to be tighter? Mast appears to stay in column.

Inquiring minds want to know.
TA
Gary