No, but I suspect the vacuum pump for the brake booster may need repair. I took it by a mechanic friend today to show him and he pointed out things under the hood; like the vacuum pump and the fuel filter.
I always thought Jake brakes worked by lifting the whole camshaft; but these seem to be the opposite of an exhaust cut-out:
Jacobs Vehicle Systems | Exhaust Brakes
I think I would prefer the KERS solution.