Ok I've has a good ol shufty around the rated and slated HPT thread and everyone has slightly diffeneing views on each test but can somone go through the basics with me...I've never had to use the things before!! Ok the test for hormone levels so the lower the miu levels it can detect the better right? What the heck is an evap line? Are there any pitfalls to using the cheaper tests rathe than CB digital for example??