my 02
I recently bought the Nordskog digital boost gauge and a few others. The sender comes with its own two wire harness and requires a ground and another wire goes to the gauge. It also requires a vacuum source, of course.
For me, the gauge reads too slowly. I can floor it for five or six seconds and the gauge will barely creep to show 5 lbs. of boost whereas my old VDO would move instantly (before it was stolen out of my car). Also, if the gauge doesn't show a given number long enough, the memory feature doesn't record it. Lastly, I question its accuracy because sometimes it reads 1 lb. of boost when I'm at idle and other times it flickers between 1 and 0 lbs. during no boost conditions.
I can't speak for all Nordskog gauges, but my money will go to VDO the next time around.