What kind of power are you talking? If you are talking a stockish 1977 440 and you want quiet, you don't need 2.5" dual exhaust. The best driving, snappiest throttle, best pulling 440 I ever had was a factory original 350 hp 440 in a 67 Chrysler. It had a 2.5" single exhaust.
If you are like most, and simply must have an exhaust system that is 50% bigger than you need, get a dual system with 2.5" headpipes, necked down to 2.25" mufflers and 2.25" tail pipes. Get the longest full body muffler that will fit from Midas. This is basically what the factory used on the highest hp 440 it offered. This will support an honest 375 hp.
I've made over 400 hp with that system with a DynoMax full body (25.5" long) 2.25" Super Turbo muffler (17747).
In the future you can step up the muffler and tail pipe size to 2.5" and easily support +450 hp.
2.25 would cut some sound, but hymn me in for future upgrades. Both engine rebuild and just adding headers.
Kinda a curious response. Dyno tests of back to back same engine with just bigger exhaust shows you gain power everywhere with larger pipes that the myth holds as “being bigger than you need.” Also guys like ray evernham will tell you to step your exhaust size bigger as you go. A bean counter will tell you it’s “good enough” for what your doing if you can cut a few cents out of a trillion cars and make packaging easier on an assemble line.
There really is a lot to be gained by putting on a big honking exhaust. I can think of a couple cars it really stood out on after switching what should’ve been an ok setup. I just have never one together with being quiet as part of the package. Some things came out fairly tame, others roared. Last car I did ended up with a drone around 2500. Sold it before I got around to trying resonators.
