CobraKLR - The 1/8 PT to 1/8NPT adaptor will fit into a 1/8NPT bung. The stock sized bung is different. We have a fitting that allow you to fit the EGT probe into the stock EGT bung BUT, clearance is a huge issue. With the extra fitting + the Omori EGT bung + the EGT probe, the whole piece juts out too far from the uppipe and interferes with a engine component - forgot what that piece is but I know it just does fit due to clearance.
The adaptor is really meant for the EGT probe to be inserted into a 1/8 NPT bung.
Call us if this makes no sense.