You can't remove the second one... you 02 sensor behind it will be reading wrong and screw up your performance. My truck only has one and its near the manifolds so I didn't have a problem taking off a cat. Just replace both cats with one highflow and put your sensors back on where they were originally.

 

tru tat the truck will run alittle rich ,mine did the i just advanced the timming abit.performance has changed since.hollowed out cats sounds so horrible

 

I have a '94 F150 and my o2 sensor is before the cats, but my egr vavle sensor thingy is between the cat and the resonator. Does this make a big deal if I cut both cats off?

 

My front cat is clogged and I’m wanting to remove it. Before the cat is the O2 sensor and 2 pipes enter the cat. How can I run a single pipe down to my muffler?

 

Although I am not a bottle fix it guy, i have been successful on this situation using Rislone cat cleaner............