While trying to replace downstream O2 sensor in my 2002 Odyssey, I noticed that there are two cuts in my exhaust pipes, one before and one after the catalytic converter. The cuts are through the pipes, and almost 360 degree circumferential (as far as I can check). Are these cuts intentional? Will that affect the exhaust function such as leaking? I am the original owner, and have never had exhaust work done on this car.