I'm telling you that car has a snarling, racey sound that I have yet to hear on any other 5.0 with Magnaflows. It just goes to show that the entire setup makes a difference. I'm running Magnaflows on both my cars and I am not thrilled at all. lol I do prefer them for my daily ('92) simply because I wanted the quietest muffler I could get for the money.
For my '90 I will be going back to chambered but not before I upgrade to a high-quality, stainless steel, true X-pipe. I don't care for the "pitter-patter" idle but it's not a deal breaker.
I think the big part is like mentioned above, the Dr. Gas X pipe. It's a true X, not a clamshell design like BBK or Bassani sell. It's basically two 45 degree bends saimesed together. I think the clamshell style X's sound more like Pro Chambers to me, or even closer to an H than a real X sounds. The rest of the exhaust is just some old rusty Mac full lengths.
This'll sound crazy, but as soon as i'm able, i'm gonna put on two different brand/style mufflers and see what it sounds like. It'll probably suck but i like doing things different and who knows it might sound awesome.