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..
Your exhaust system consists of Headers/Exhaust Manifolds, Mid pipe, and Cat Back.
The Pro Chamber is a Mid pipe, it is called an offroad pipe because it does not have Catalytic converters. Most Cross Over pipes either have an H or X crossover.
The Pro-Chamber has more of a BOX at crossover. They sound amazing with 2 Chamber Flow Master Mufflers.
BTW, all you need is the NAPA part number listed above. Unscrew the drivers side manifold studs after you take out the stock midpipe and replace them with the 2 studs in the kit. The ones in the kit are identical to stock but just dont have a shoulder on them and are all thread so you can tighten down the flange completely to seal it all. As for the gasket RE-USE THE STOCK GASKET. If you mess with pulling off the stock one and buying a new ford one etc. your going to cause your self plenty of nightmares. The stock one should stay stuck on the exhaust manifold (header) and all you have to do is bolt up the new one once you gets your pipes all lined up.
It sounds unreal with flowmasters...the two are a match made in heaven . Now if only i can work out getting the prochamber to match some hooker style long tubes (loses load thinking about it...).