I know the wide band is a tuning aid and is not a end all be all iron clad deal, but by using it I can make changes and see what it does and how the car reacts to it by watching the time slip's also, if by leaning it out some and it slow's or mph drops down,then I know I went the wrong way and it actually likes a little more fuel than I thought,and vise versa, I did pull a plug and they have colored some but it is a lighter grey than ever before and the collectors are lighter in color than before so to me that is a plus, the biggest thing I was happy about, was with Dom's help and guidence I never had the first hiccup, that just made my job even easier because I am not chasing a gremlin while trying to find the tune.