Im sure that its accurate, but there isnt any way of distinguishing small increments in boost. eg my Blitz boost guage goes like 0, 0.1,0.2,0.3,0.4,0.5,0.6 bar etc the stocky goes -7x100mmHG, 0, +7x100mmHG, it fine to guess but can you tell the difference between 12psi and 13psi? If your running a stock turbo it might mean the diiference between blowing it up or extending its life. For the price of $60 to $160 its small invetment.
Plus they look good hehe