Biggest waste of money you'll spend... until you get 1/2 down a good size hill.
After installing mine I've only had to use foot brake one time and that was on Lewiston hill. That includes I-5 from border to border and I-90 Seattle to Yellowstone.
Wife no longer yells at me going down hill. No longer grips the door handle with a death grip. You guessed it, everything goes to fast for her.
She hears it come on and it's like a cat purring to her. She sits back and relaxes and so contended. (I love that!)
Years ago used to come off those hills with freight trailers. No jake brake and no trailer spike, no nothing. Spent a lot of time watching the mirrors waiting for blue smoke to start coming off trailer tires. I thought it was something when freight trucks got a 13 speed. Really thought I went to heaven when company sprung for jake brakes..
Have had zero problems with BD exhaust brake in 2001 Dodge 3/4 towing 9,000 pds.
(Only 120 pounds of wife but used to make a lot more noise than exhaust brake does):B
Pay in once and be happy. Money saved in long run IMO.
