Thing is, for every increase in db rating the actual volume of noise doubles. Anything over 50 can be quite loud if you are close to it. I've seen some 'ratings' that claim like 52 db, but at 20 feet or more - those are flat misleading since you'll easily be within that distance.
As an example, the 3000 Honda heavy one is down to 47 db and extremely quiet, but also over 100 lbs. There's a local hand-made ice cream company that vends at events and has one on the front of their trailer. You can't hardly hear it only six feet away. We've two 2400 Yamaha's that are slightly louder (52 db I think), but still aren't much at the same distance although you can definitely hear them.
In order to really find out how loud a given make/model is, you've got to have it running with a load and listen to it yourself. Also, some make much more noise with a heavy load than a light one.
'06 F350 TD, Softopper, airbags, AeroShield, coolant filter
'10 3665RE Hickory edition, wetbolts, Firestone LTs, Trimetric Battery Monitor, 4x100w panels & Morningstar TS-45, still tweeking.