I recently bought a Innovate wideband kit and need to install the 02 sensor in my downpipe. The sensor needs to be installed as far downstream as posible before the flex section. Im not the best welder so don't rag on me, I do my best and yes, it does seal.

Step 1, pic 1: Start w/ your downpipe. As you can see, I cleaned up the area where I will be welding w/ a grinder. You can also see the 02 bung that I am using.

Step 2, pic 2: Drill a small hole first and gradually go larger untill you get a 1 in hole.

Step 3, pic 3: As you can see, I intentionally went a tad larger than 1in so I could recess my bung into the downpipe, to give it a cleaner look, as well as a better weldling area.

Step 4, pic 4: First, tack the bung in place and make sure its where you want it facing, then continue to weld it all up good and tight.

Step 5, pic 5: Here is what my weld job looked like after I finished it all up. No, it doesn't leak. Now's a good time to clean up any "pops" that might have come from the welding, like in the threads, clean these out now w/ a wire brush and a flathead screwdriver.

Step 6, pic 6: Thread in the wideband 02 sensor and use some antiseaze if you ever need to remove it later, youll be glad you did. Tighten down the sensor now.

Step 7, pic 7: Here is what the finished product looked like. Get the sensor welded as close to flex section as possible, as it was a tight fit clearin my oil pan w/ the sensor sticking up like it does.

All done. Enjoy!