I would like to add a performance dual exhaust set up to my 5.4L '04 FX4 while keeping the cost to a minimum. My questions would be:

2 mufflers with true duals? do I need to add a cat?

or

1in-2out single muffler?

1in - 1out then Y ?

2in- 2out single muffler?

Anyone done their '04 5.4 yet and how did you do it?

Pics would be nice if you have them. A pic is worth a thousand words to these muffler shop grunts.

Other question is..I've tried searching everywhere for this spec, but what is the factory exhaust Diameter on this powertrain? Particularly pre-muffler. It looks like a 2.5" but when I take the tape measure out, it seems more like a 3"

Thanks