yep tubtar, doing the same thing everytime, even at different rebuilds is the problem. This is why i'm asking about the one in the OP. not having seen one I was hoping for some feedback, its available thru Summit so i can consolidate a few items to save on freight.I'm down under so if i shop wisely i get a few things at a reasonable rate. The one i'm looking at is compact & looks almost idiot proof & being consistant, data from 1 rebuild check to the next should be consistant. Really cant see that happening with an on engine tester.