I actually stuffed a 70 series (one of them) under the passenger seat. It did a good job. By no means was it stock quiet, but it was quiet enough to hear the massive wind noise.
Exhaust sound is such a mystical art. Different engines and different exhaust systems will make such completely different sounds. I was trying to louden up a truck at work once so I disected a new muffler, found a single wall that seperated inlet from outlet. Took the actual muffler, cut the top off, cut that wall out, welded the top back on. installed in the truck it looked 100% stock. And sounded 99% stock. You could see daylight through that muffler. Still quiet as could be. Took off the exhaust after the cats, loud, evil, nasty noises. just a bit of pipe and and a hollow can made a church mouse out of it. Some aftermarket muffler and back to uncivilized beast. Sound clip at the
55 second mark and you will hate that sound on the highway. We did another and open pipe and a pair of little glass pack resonaters, we expected to be loud and obnoxious, the perfect shop truck. Absolutly perfect. It does drone at highway speeds but the idle is just enough to let you know it is there and when you get on it there is a pleasent sound that is a bit more civilized that the sound clip, but you can still hear it a couple blocks away.
Engines will also have a huge influence on sound. Compression and valve timing are huge influences to what an exhaust sounds like. I have alwyas had to play a little to get the exhaust I wanted on every project. I have never found just the right choice on the first go around.
My ranger project probably got the most extensive tuning of an exhaust system I ever did. The final version was one of the neatest ones I ever did. Took a stock replacment muffler for some Dodge truck. And put a turbo wastegate (some cheapy eBay part) to open a second bypass channel around the muffler. I had so much fun with that! It was like being back in highschool again. Drive around relitivly peaceful, push the button and the crackle of a straight pipe. Kept a picture of it.