Exhausts on a K1100- What to do with the o2?

I’ve been riding my K for about 6 months now, and love it. But with the more aggressive look on my bike, I’m looking to shed some weight and get a smaller exhaust. My K1100 has the factory unit, and it’s in perfect condition, so I don’t really want to cut it up because I read they are getting harder to find.

What I see is finding a set of k100 headers, the 4in1 collector from BSK and a smaller, mild silencer.
My question is, where is everyone putting an 02 sensor? Do you just drill a hole in the 2” pipe and weld in a nut? Or do I have to do something with the cat. Converter?

Help would be appriciated.
Thanks!

(Here’s an older picture of the bike, sans rearsets and new bars.)
https://imgur.com/a/eVzW0hx

For my K1100, I just bought a Remus non-cat header and muffler that has the bung in it. But yes, you could weld one in. Here is a typical one, but I didn't check it for size and thread pitch...

https://www.thoroughbreddiesel.com/1188/?gclid=CjwKCAiAjNjgBRAgEiwAGLlf2uMS__PrUdWYnNjHSbiugyozNdVp5raKnzUEsDdsQYZj30H839qTOxoCCi0QAvD_BwE

If you are willing to cut up your current exhaust, you could fit a collector such as this one and go muffler shopping.

http://www.bskspeedworks.co.uk/k-collector.html