Brian,Yes I have the on head tester. The LSM piece works well. I check them with a bench top unit first upon install but we use the on head to keep track of them during the season. The removal tool from LSM is nice and works well. The Buxton piece is easier to use but on this engine in my car it does not fit well due to engine set back. IIRC LSM will give you a break on price if you buy the removal tool and tester together. Lance is a great guy and a heck of a racer as well.