Blow off valve?

[Dm23]

So my buddy with a 18 L5P wants to do a blow off valve. I told him that he really doesn't need it, but he insists that he wants it just for the sound. Any of you guys have any input into this topic? His truck has a stock turbo, but does have weight reduction. I really dont think he needs it, but what would you all say?

 

[MAXX IT OUT]

Per usual, he wants it, not needs it. Yes, you can put a BOV on a diesel, but since a diesel doesn't pull vacuum, due to no throttle blade it can't be done like a gas car. BD, turbosmart, and other make a kit.