11. Blow-off valves or BOV or similar
Since people insist upon asking about these devices, they need to be discussed ... The purpose of a "blow-off valve" or "diverter valve" on a gasoline engine is to give boost pressure someplace to go when the throttle plate is abruptly closed, to prevent operating the compressor in the "surge" regime. Since a diesel engine doesn't have a throttle plate, a gadget like this serves absolutely no purpose and has no business anywhere on a diesel engine. "But I like the cool noise ..." Too bad, this discussion is focused on things that WORK. Even if you manage to find some way to make such a device work, the noise of people "in the know" laughing at you because they realize that it has absolutely no place on your engine will drown out the noise that the device itself makes.
Installation: Impossible. Cannot be made to work even if you insist upon it.
Advantages: None.
Disadvantages: Won't work. People who actually know how a diesel engine works will laugh at you for even considering it. You are your own warranty.
Cost factor: Too much, all things considered.
Cautions specific to this modification: Won't accomplish anything.
Suggested modifications in parallel: Irrelevant.
"Bang for the Buck": One hundred percent total waste of time and money.
What if I want more? Do something that actually accomplishes something ...