The first incarnation of my '59 Chevy pickup, I put a 350 out of a wrecked '67 Camaro in it; had long tube headers into 2-1/2" tubing, turbo mufflers (don't remember the brand, but got them at So Cal Speed), and about 30" of tubing behind the muffs int turn downs right by the rear axle. It had a nice Rrumble, but no rap at all, and the only drone I got was at about 50 - 55 on the freeway - never noticed it on city streets - it was quite civil. That engine went away, to the point I could run it, but not trust it, and the truck got grounded for a while before I got around to getting another engine built for it, only being started and moved once in a while. Some years later, I got around to getting it re-done, needed it for getting to work; put a newly built 350 in it, and re-used the long tubes, but the turbo mufflers were rusted from not getting hot enough to dry out the accumulated condensation when it got started and moved from time to time, so I grabbed some no name brand 30" glass packs for it just to get it driveable; they were 2-1/2" in and out with a 2-1/4" core tube with louver type perforations, and short turn downs right out of the mufflers, still just a foot or so ahead of the rear axle. I got them in, and started it up - wow, what a difference. It had a deep throbbing Rrumble (mild cam in the engine), and when I got on it, it sounded great, nice deep growl going down the road at loud pedal, but really mild at cruise. The first time I took it to the local mall, I set off most of the car alarms in the parking lot. I was pretty pleased to get that result for so cheap. In general, though, the larger the tail pipe tubing, and the longer, the deeper the tone at the tip will be; smaller tubing will raise the note of the tone and introduce rap in a full length tail pipe. "H' and "X" pipes will smooth out the pulses and reduce perceived rumble, but may nor may not affect the tone. So, I guess the moral of my story is, you can't really tell what you're going to get until you open the box of chocolates.

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