I had duals on my 1st trooper, a 91 2.8 (dual exit muffler IIRC). I ended up just changing to single 2.5" after the cat to improve my departure angle and to see what kind of performance I'd get. small increase in 3k+ rpm power and maybe a little tiny bit better mpg, but nothing spectacular. nothing that I would do until it needed new exhaust.

Any good exhaust shop should be able to do what you need. If money wasn't an object, I'd probably get it new from the manifolds back. dual hi-flow cats, h-pipe, then dual mufflers. mandrel bends and either 2" or 2.25" pipe.

I hear a lot of good things about spintech products, and when I get to the point where I have to redo my exhaust, I'm going to try them out.