Originally Posted by Jakeepoo3

I love my mother earth very much. But your plan sounds redundant. Headers and cats?? It's not worth even putting on headers if you're running the cats. To answer your question the cats on mine were welded. If you want the same configuration weld flanges to the headers and get the cats with flanges. Simply bolt together. Your truck won't smell bad without cats after a proper air fuel ratio tune which you will have to get done afterwards. You won't need a dummy downstream sensor if you're replacing the cats correctly. My cats just started going bad. I have downstream dummy's for now so my truck runs properly. I'm going to straight pipe the cat sections get a ton of precious metal cash and use it on a free air fuel tune. Maybe have extra free $ to throw at some headers. After tuned right your talking substantial horsepower and torque gains. Probably better gas mileage. For free. I'm more worried about our planet being destroyed for profit than a catalytic converter.