I noticed that there is an additional oxygen sensor behind the main converter on my 98 GSX (non CA) that is threaded into a restricitive looking coupler that connects the converter to the rest of the exhaust.

I see no sense in installing this restrictive piece behind a new 2.5" converter and "Y" pipe.

Would the sensor work right (and not throw a code) if a person simply drilled a hole in a custom "B" pipe right behind the converter and welded a fitting to it for the oxygen sensor? The exhaust flow to the sensor would be a lot less direct this way.... which is my main reason for
concern. Have you guys tried this? If so, what were the results?

I'd purchase a "Y" pipe and converter if I KNEW it would work.

Thanks!