Here ya go for directions of a 'plain vanilla' rig tune up: http://www.riggingandsails.com/pdf/selden-tuning.pdf
- note the section of fine tuning rig tension WITHOUT a tension gage, just a meter stick and some tape.
The above is probably the most comprehensive rig tuning guide available on the net. Plus, I suggest that your follow Faster's advice about the loose shrouds at 20+kts. .... BUT then mark the turnbuckles and remeasure the static tension when at the dock AND with the boat pulled over by its masthead to the approximate heel angle as when in 20% knots, etc. as you dont want your rigging to continually exceed 30% of ultimate tension ... leads to 'fatigue' and that greatly lowers the service life of the rigging and its components. Just use a halyard, and pull the boat over to that heel angle and then take your reading on the meter stick - you dont want the tension (preloaded static tension plus
additional tension that causes the heeling) at that max. heel angle to much exceed 30%. No need to exceed 45° heel angle when artificially heeling the boat over with a halyard - because of 'trigonometry'