These adapters will not work well. An old trick was to use the spark plug non-foulers to back the )2 sensor out of the exhaust stream when you had a bad catalytic convertor or had removed the convertor. As far as why they are sold, the same reason "performance chips" are sold all over ebay, that plug into your air temp sensor. It is cheap and easy and someone will buy it hoping for a cheap fix/gain. Harley (and I am sure others) sell a toll to redrill and tap the stock location to an 18mm. Since this is sold by them (and required to upgrade to their wideband system), I would say there is enough meat to have someone do this. As far as getting a ThunderMax, I would try ebay, having an out of state friend send it to you, or my favorite option but not feasible... move out of Cali! lol Hope this helps.