I find exhaust brake on my truck is inversely proportional to speed and not quite like a Jake Brake (which I have no experience off) and in 'my experience', works even more effectively on steeper gradients.I did notice yesterday from 70 MPH down hill on off ramp I hit brakes a couple of times and I think I heard or felt a slow down, So when you just hit the brakes it applies more exhaust braking, I'm really trying hard not to hit brakes to hard because of the new front Rotors and Pads for at least a couple of hundred miles, OEM Rotors were warped from 1st owner.