Learned from the Yahoo Wide Format Printer group.
Under the paper configuration in the driver adjust the feed rate. For the Breathing Color 800M I found +35 worked, on the Lyve I have it set at +42. Somerset Velvet and BC's Elegance Velvet don't shrink printing or laminating.
This seems to work for me, the canvas is laminated after printing so the shrinkage also takes that into account. I save each of these setting as a custom setting in the print driver. The alignment of the print layout is also important since it appears that the canvas only shrinks in one direction against the warp. Your mileage may vary with alternate canvases.
Mark Prins
Inanda Images