The one from newspeedmaster is a great device...simple and effective...with 4 tubes as well. I like it better than the yardstick I used at first...mostly because it is smaller and the fear of mercury keeps the wife away from it!

Are you classified as human? Negative...I am a meat popcicle. 06 Speedmaster. 790 Cams, Supertrapp Exhaust, AI removed, 150 Mains, Thruxton needles, Airbox removed with K&N Pods 180 degrees.