Class A engine noise.

Many improvements over that past 20 years. New 6 spd transmission helps. My 2016 is quite quiet when going down roads but will make noise when it down shifts to go up a hill.

engine right next to the engine ?? never, rear engine diesel a lot less noice.

Dont know if you are looking at a new unit, but the 7.3 makes it's power at lower rpm's. Which should help some along with the extra gears in the newer trannies.

I'm glad to hear you're back. I am new here. I am agree with wildtoad.

One big change since '99 is the higher floors. Both because of taller frames (with the 24 and 26k GVWRs) and the raised sub-floors to allow full size baggage compartments below the slides. This means the doghouses are smaller, and there is more room for insulation.

I test drove a Canyon Star 3920 (the toy hauler), and engine noise was very non-intrusive. The normal coach noises were far more annoying.

The 7.3L gas motor is quite a bit shorter than the V10, so once they are in full production, the coach builders should be able to build nearly flat engine covers. Seems like the first ones one are still using the V10 covers. Ford included. Current 7.3L E450 uses the V10 engine cover, but they say a smaller cover is coming out in January.

I added a noise/vibration reducing lining to the doghouse area of our V-10 powered F53 chassis class A motorhome. Now my wife and I can hold normal conversations even when the engine winds up to ~4500 RPM on the steeper hills. The lining also reduced the heat from the doghouse. I don't see the brand I used listed any more, but there are several other brands that look similar.

It all depends on how he MH was built. My 2012 is just as quiet as my 02 Excursion with the V-10. Yes it will still rev but a higher end gas class A will be quieter than an entry level model.
I was worried about mine because I rear all the horror stories about needing to yell back and forth to have a conversation. Not necessary in mine.

My Workhorse (Chevy 8.1 no longer made as I understand though I heard they Finally came out with a replacement) is not too bad normally.

But when the Fans kick in on HIGH.. WOW is it loud
(they don't often do that)