Please don't read too much into these internet 'my muffler only flows 1800cfm and his flows 2600cfm...what am I going to do' whine and moan threads.
Lest be honest; most true performance mufflers will be able to flow more air through it than your car can generate. Doesn't mean you need it. And it doesn't mean its hurting you.
If its about noise, a 3-chamber crossflow muffler; or 2 2-chamber mufflers with a cross over of some type are more than adequate.
Guys love to convince each other that they need long tube headers (which aren't tuned to that specific motor), 3" pipes, 2 chamber flowbastids and an X pipe will magically 'make' power.
If you want to reduce drone, run the pipes over the axle, use an X pipe and a chambered welded seam muffler with some sort of accoustic wrap (like fiberglass) similar to a magnaflow.
Run 2.25 pipe if you have manifolds, 2.5" pipe if you have worked heads and headers.