If your vehicle runs near the manufacturers standard boost & you can fit the intercooler you want properly, then a plennum will be a waste of most of it's cost. If you are upping the boost levels by approx. 30% or more (some of us are very greedy!), then I would read on & give it some thought.
Even though we were modifying Diesel manifolds 6 years ago, I would not have been game to put this page on our site. I've always said that a diesel engine is the same as a petrol engine, "modify it properly & you will increase Torque & Horsepower & decrease fuel consumption", in fact, it was easier, as the diesels were mostly still based on the truck design that was used to deliver material to Noah for his ark (maybe not quite that early), & so not suited to our power delivery needs of a people mover.
Now, with a few LeMans wins & being hobbled too slow them down, & the power & revs from the modern auto diesel ( & I must say, Europe has caught the Japanese napping) is changing everyone's thoughts & perception of a diesel engine. Allot of these giant gains have come from 'the good ol hot rod boys' principles from the '50s - more air, more compression, more fuel, more revs, less weight - hang on tight ! The only one that's missing is more spark ! They are all just a pump.
A diesel plennum has one big difference to a petrol version that we are used to dealing with, It needs a smaller internal volume. Minimum turbulence & eddying (important),  the correct volume of air for the next stroke, as even distribution to each port as possible. Now, this last one is not as important as on a petrol engine. A diesel has the ability too run noticeably leaner than a petrol without damage ! BUT there is a limit, & it's expensive ! With a highly tuned petrol engine, a cylinder that is not receiving the same amount of air, will loose ring tension, melt the piston, eat the head gasket, burn the exhaust valve, usually in that order. Because a diesel engine is designed for a high compression, it is so much more over engineered & robust & doesn't have ignition to fire the fuel mixture regardless, they are much more tolerant to uneven port flow. BUT, all the components in that cylinder will wear out faster ! We are talking valve guides & springs, valves & valve seats, headgasket around that cylinder, rings- especially top compression, & the top of the cylinder wall.
No scare mongering for a sale here. As I said at the start, up too approx. 30% boost increase, you don't have to think about the above. Depending on the engine design & construction, the more you lean on it from this, the closer you need too look at the intake.