The longer the muffler case, typically the quieter it is. Same goes for smaller OD tailpipes.
Going too long though complicates the tailpipe bend after the muffler as far as clearing the shocks & rear axle.
I'm usually 18" max length on mufflers, and for something you don't want to be too loud, look at:
Dynomax Super Turbo
Magnaflow equivalent
Walker "Hemi" muffler
I liked the tone of the Dynomax on a fairly healthy 383 RR, not tinny, not too deep, was throaty & crisp.
Ran the same on a healthy Hemi RR: headers, H-pipe, full 2.5", modified (2.5 inlet) tips, perfect.
The tips seem to sound better than non-tips, my guess is because of their chamber.
X-pipe will usually have the effect of smoothing the pulses and giving a higher pitch to the sound. H will leave most of the pulse in there.
I'd be tempted to run 2.5" tailpipe on a 440, and tips are available nowadays for 2.25 & 2.5 entry.
That said, sound is kind of subjective: on a wagon I did, I tried 3 types of mufflers before I was happy; my exhaust guy still chuckles about that one, but the architecture of a wagon (they're like a drum) complicates that.