How many Cats?

Its my understanding that the driver side has the heat shield, as the fuel lines run down that side....I really never bothered to look into this.

 

You can remove the rear 2 cats without harming anything.

 

You can, but I am uncertain as to how the sensors will respond to the high flows. I have heard reports of ECU's not "liking" high flow CAT's. I mean you may throw a CEL (check engine light) code for a faulty CAT even though it will function properly. There is also a way around this though.

Here is a possible scenario: You replace the front 2 CAT's (they are the only ones the ECU monitors) with the high flows. The ECU throws a P0420 (bad CAT code). This code will be genereated from the reading of the rear O2 sensor. It will register Bank 1, 2, or both.

The correction: You can purchase an O2 simulator from URDUSA.com that will tell the ECU the CAT(s) are fine.

 

If I were in your shoes using your ideas, this is how I would approach it. I would replace the front CAT's with the high flows and monitor the performance for at least four tank fills. If no negative effects are noticed (ie: CEL's, performance losses, etc), I would consider it a success.

If the truck throws a CEL(s) for bad CAT's, I would purchase the O2 simulator.

Keep the stock set-up in case you should have to go back to it at a later time. The second set of CAT's are unnecessary.

 

I cannot answer that question with certainty. I would suggest running a set of before and after dyno's to verify any performance change.