Discovered Something Interesting About Piezo Crosstalk... in James Tyler Variax Guitars / Workbench HD Posted March 10, 2014 Regarding string gauge,.... If you want to use 9's, that's okay,.... but you'll need to take it to a guitar tech to have the set-up adjusted for that gauge set. When you change gauges, you change the tension, when you change the tension, the set-up is off and needs to be adjusted. That info might not be in the brochures, because it's just a common aspect of all guitars. Change anything that alters the string tension, and you alter the set-up. It's like that on all guitars, not just JTV's. Also, climate of your location also affects the set-up. When you get a guitar back from a distant shop, the set-up should be done with your location in mind, so give it a couple days or more to settle in. If it is still a little off, take it to a local guitar tech for that final dial-in.