If your going with dual in and dual out, then why bother with a single muffler. Just get a pair of Magna flow high flow 18" or 22" then go true dual. You can keep the resonators if you like. But note, a single muffler with dual in and dual out does not make for a true dual setup. Nor do you need an X or H pipe on your hemi. I know this for a fact, as I have a true dual setup using a pair of Aero Turbine mufflers AT2525. you can hear them on youtube under Aero Turbines dual exhaust.