I would venture to say that most of these guys that think they have to improve on hydrovac brakes have never driven a truck with a properly functioning hydrovac system. I grew up riding and later driving two ton bobtails delivering gasoline in the Texas Hill Country. From when I first started riding along in the late 1940'S until I bought a semi with air brakes in 1964 all we had was hydrovacs. And they would stop a 2000 gallon load of gasoline just fine. And we went faster than most people realize. We weren't afraid to run our gas GMCs up to 70 mph and we had no trouble stopping them. I wonder were this guy went to buy brake parts. I had an Isuzu NPR for a while. I bought rear drums for less than $100 each 10 years ago. I notice they are up to $130 now.
