The venerable Pentastar 3.6 V6 in the Jeep beside it there is significantly quieter than the noise from the tyres, unless you stamp on the pedal and wind it up. It has a nice note when under heavy load but it's not really audible in normal driving.
The Challenger actually hits the maximum Federal noise limit when you open it up, which is significantly louder than the EU regulation. It's brash and uncouth and I love it.
The Chieftain really needs a better quality silencer to get rid of the rasp but retain the engine note, it sounds a little bit too "rat rod with no silencers" as it is. You can hardly hear the exhaust from the driver's seat though, at idle all you can hear is the camshaft, fan and alternator. Putting your foot down through a tunnel you can really hear it though.
Horses for courses, really