I'll have to agree about the adjustable fuel pressure regulator, That is now on my list of things to buy. Checking the plug will always be the best way to know about air/fuel ratios but a guage will let me know that I should check and what I should look for. No doubt that I'm going about this with more caution than may be needed, Thats just the way I'm comfortable with it. It is difficult to sort through alot of this information/mis-information that is readily available on the web.I've read posts on that other website from folks who some how had major problems despite the safety features that should have prevented them. Not everything works 100% on my car, but I doubt a malfunctioning rear widow washer is going to cause catastrophic failure. The comment about the fuel cut-off "its nice to know it works" my question is "how will I know on the day that it doesent?" I think that what I'm doing is simply setting my beloved Volvo up to be able to give me correct and timely information about how it is doing with more boost.