Join Date: Jan 2018
Location: Bonners Ferry, ID
I saw the PM SierraGuy sent but decided to respond here as it might be of interest to others. The diesel noise has a life of its own through the years. My direct experience started with testing out 855Ds. Loud. So when I bought mine 4-5 years ago, I made sure the cab had the inner liner and added the "Sound Reduction Kit". That was essentially bent metal panels which covered any remaining openings between the engine and cab. The noise became tolerable. When I purchased an 825R, I noted several sound attenuating features over the 865M including a headliner and back panel covering. The noise is considerably reduced from my 855D. I don't know how much 865R upgrades you can lay in, but I'd take a serious look at the headliner and what you have for the existing rear cab panel. If it is just sheet steel, consider a thin glue on piece of foam.
I will alter the sound when I turbo this one up too. Overall the sound level is the same. It's just the type of sound with the engine being much happier that I like. That and a boost up to around 32hp. Big difference on the hills under load.
Last edited by CaptSeabee; Yesterday at 09:58 PM.