My experience -
I frequently travel to the N.C. mountains (Boone on Hwy 421 to be specific) and my trip home includes 4 miles of an 8% downward grade. The speed limit for vehicles is 55 (35 for large trucks). It has a few turnouts and runaway ramps so it can get pretty fun.
I set my cruise on 55 on the nose and enable the exhaust brake. With only one exception, my truck never goes above 57MPH and I only have to touch the brake pedal ONE time and that is for one specific curve that has a sign to reduce speed to 45. I touch the brake pedal to force the truck down to 50 but only for a moment, and enable cruise again right after the curve and I am still good for the rest of the 4 mile descent.
For the entire descent, the RPMs ride between 3,500-4,000 and I definately can "hear" the loud exhaust brake beyond the normal high-rev of lower gears.
In comparison, when I used to make this trip on my 2013 Camry (V6 auto) and my wife's 2013 Highlander (also V6), I could never do so without riding the brakes and dropping the gear shift down to keep speed reduced.
My experience FWIW.
2017 GMC Canyon 4x4 Diesel
Last edited by MTShipp; 06-18-2017 at 02:02 PM.
Reason: Corrected my RPM range