See this is what I am looking for...straight up answers, I appreciate that. Yeah I hear you loud and clear...So how do I go about porting my stock headers? What do you mean by a 2 1/4 cat backbone? So no mid-pipe? Just cut the existing piping after the cats and then run new piping to a set of magnaflows? Sorry for being ignorant but I need things spelled out for me to visualize it. So again no H or X pipe just straight to magnaflows and out?

You'd still be using the stock pipes and exhaust set up that came factory on the car. The term "cat back" refers to all the piping down stream of the cats. I can't remember off the top of my head what the 3.8s used, I think it already is 2.25 inch piping. If it is, and if it's mandrel bent from the factory (the bends are nice and smooth, not crinkled) then all you'd have to do is have a set of magnaflows put on. If not you'd have to order a cat back for the 3.8s or have someone make you up a custom exhaust system.

Yeah but from what I have heard, bolt on catback systems are restricting and dont really give you any performance just the LOOK. Remember I want both, it would make sense to go duals for sure. As far as magnaflows, I have talked to a couple of shop owners and they are magnaflow dealers but dont sell it cuz its crap for the mustang. I know the flowmasters are marketed really well for the mustang but again this is what I have heard and found out in my research. Plus the stock system on a 3.8 comes with a y pipe, which makes it hard to do duals properly and minmizes performance.

Personally I dont see anything wrong with cats, they produce a little back pressure witch is good. No back pressure burn out your valves.
Those new Performance cats are great there is nothing wrong with them at all....Nows its just hear say.
Just my $0.02

So should I leave my rear cats in and go into a h pipe then to 2 flows 40s

You know dude, do what you want. It's your car after all. if you're peeps are telling you magnaflow is crap they are probably telling you crack is good. Whatevs. best of luck to you and your buddies running 16s with a tailwind.