Purchased the Stainless steel Bazzaz Bung for my Z-AFM to work. I'm using it on a stainless Yoshimura R77 midpipe
THe bung that comes with it is the standard Honda size. When you use the Wide band Sensor you need the larger 18mm bung. You can save some money by preparing the hole using a grinder remove the old bung and drill the hole to the ID size of the new one. Take it to a good metal fab shop that has an experienced TIG welder and expect to pay around $60 to get it done right.