swapped89

It is a 99 V6 3.4 5speed 4x4.
Just put cat-back exhaust on with 40 series flow. 2.25'' pipe
Want to make it louder by hollowing a cat.
It has two cats and the O2 censor is behind both of them. which cat should i hollow out? will this make the engine run bad or just turn on the engine light(because of the O2 censor)?
I was thinking about moving the censor in front of the rear cat but behind the first cat- and hollowing the rear cat.
Has anyone ever done this?
Another idea is that if i hollow the first cat the second one is close enough to the O2 censor that it wont through codes or turn on the engine light.
example of stock- exhaust manifold-1st cat-pipe-2nd cat- O2 censor- muffler.

example of what i want to do.
exhaust manifold-1st cat-pipe-O2 censor-2nd cat/hollowed- muffler
Please give examples of what you have done.
I dont care if you think its illegal.