Have you driven other similar motorhome to have a comparison as to power and noise? These coaches are not fast, especially in a large gasser. As for noise, the engine is right next to you and under load it will downshift to higher rpm and maybe the clutched cooling fan kicked on which can be quite a roar by itself.
Vince and Susan
2011 Tiffin Phaeton 40QTH (Cummins ISC/Freightliner)
Flat towing a modified 2005 Jeep (Rubicon Wrangler)
Previously a 2002 Fleetwood Pace Arrow 37A and a 1995 Safari Trek 2830.