Sorry I didn't read anywhere you had a big block. I assumed it was a 340 car. Guessing you got the 383 instead. I could see that making a difference. I guess I don't really have an answer for that. Pypes mufflers are another option also. They have straight through design as well, but they are surprisingly quiet. Not saying they are better than the Magnaflows you have now but maybe something to check out. I have a set of their race pros on my turbo mustang and it is much quieter than my dart. Now the turbo also muffles the sound. But you can't even really hear my car pull away as I drive off.
Here's a link to their site with a few Mopar sound bites with all their mufflers. The Race Pros that I have their quietiest muffler. http://pypesexhaust.com/sounds-chrysler.html
