An X or H crossover will quiet down the system, and can help with the scavenging of the exhaust (more power?). They will also even out the "blurb-blurb-blurb" sound commen on dual systems.
Choosing an exhaust system is a very personal issue, but I like the sound of LT headers into duals, with a x pipe and performance mufflers, dumped before the rear axle.
Your mileage may vary...
