Prochambers don't have cats. They are off-road midpipes. They bolt in between the the headers and the mufflers and sound amazing when put with flowmasters. If you do get one, be sure to go to a NAPA store and the exhaust manifold stud kit, part#600-1819 and swap them with the ones on the driver side or you will get a leak. The factory ones have a shoulder on them that prevents a perfect seal. And yes, there are ports for the 02 sensors, four of them. You will need to get MILS to plug into the rear 02 sensors since there are no cats..