Exhaust sounds True duals vs X-pipe or H-pipe.
I've never liked the way any cross over of any kind makes the exhaust sound. It takes a lot away from the exhaust note. Makes it flat and not crisp.
Back in the mid 90s, when I ordered my Doug Thorley headers for my 65 Valiant, I actually got old Doug hisself on the phone. Man could that old guy talk! He'd probably forgotten more about exhaust than most will ever know. Anyway, he talked in depth about how he couldn't stand any type of cross over. That all the dyno pulls they'd ever done showed little to no gain and sometimes a loss. He also said it made the exhaust note flat and just blahhhhhhh. He didn't like them. I never have either. Of course all the advertisements you see from exhaust companies will say there are gains. They want to sell stuff. I think they're much ado about not a damn thing, except making an exhaust system sound like crap.