Dynomax 17748 or 17749 are, I believe, quite close to the Hemi factory mufflers. Mine are behind a 318 with true duals, no crossover, 2 1/2" system all the way from manifolds.

At first I thought they were too quiet, but after 10,000 miles or so they got a little louder. Now they're just right. I've received compliments on how good they sound.
I believe that there is a 3" version in the Dynomax catalog. Dynomax is the performance branch of Walker.

R.