hey whats up i have a ques about the downpipe on the DRAG gen 3 on a GSR downpipe i noticed taht it has an o2 sensor port on it but there is already on on my cat in front of it and there is one after the cat i need to keep my cat so i dont know what to do with the downpipe hole get it plugged? and one more thing how come there are not flanges ? help me out please thanks alot for you time

 

There is an O2 bung in front of the cat and one after.

Drag doesn't have their downpipe flanged already. You have to have it done at a muffler shop. It'll be really cheap. I guess this way you can either run it straight thru or have a cat.