I'm running a BD Exhaust Brake with 60lb exhaust springs and love it. It sure saves on brakes!

Bob

 

I chose "Pac brake" for my 91.5 at the advise of a couple of buddys. You will need a new down pipe to start with and go for the 60 psi exaust springs to get the full braking power out of the unit. Everything I got from Pac brake fir to a tee. No grinding bending or custom fitting needed here. Very pleased with the fit and instructions. When do you plan on doing the nv4500 conversion? PM me with any questions as I did this convert in Jan last year and if you do all your homework it shouldnt take more than a day or so as mine did. Good luck.