Okay, so I know that I as many others buying this product aren't using it as the manufacturer intended, But in terms of getting my truck to pass the Texas state inspection, it totally worked and saved me several hundred dollars.I went to three mechanics prior to installing these and each one said I needed new catalytic converters based on what their diagnostic scanner tool said. I didn't have the money to make the repairs as they were quoted at being $600 plus for replacing the cats.I the car works fine and runs fine, but I couldn't drive around with my inspection sticker being expired. I considered using Sea Foam and other extreme measures like washing the cats or running lacquer thinner through my fuel system to clean out my catalytic converters, but they didn't seem like safe choices. I decided to try this anti Spark plug foulers as many people said they had good success using them to pass the inspection.... And sure enough they were right.It took a couple of days of driving about 50 miles total for the "service engine soon" light to finally turn off.I did have to drill out one of the anti foulers for each o2 sensor with a 1/2" drill bit to get it to fit over the oxygen sensor. It was a bit tough without a vice to hold it in, but clamping it with some plyers while standing on it helped secure it down for me to drill it though. The size threads I needed was 18mm and I have two exhaust pipes so I needed four anti foulers total (2 each).I know that they affect my fuel mixture and will probably be making my fuel economy worse so I will be removing them now that I have passed the inspection and hang on to them for next year. Glad to know that it works!