First, 370 HP injectors and a strong TST Power Kit will definitely cause extremely high egt's, and you will need a larger turbocharger. Somewhere around 450 HP at the wheels will then be achievable. The TST boost elbow will work with any of their torque plates with the stock 12 sq. cm. exhaust housing, but you will not be using it with these modifications. You will need a larger turbocharger, and over about 320-350 HP depending on altitude you will not get enough reduction in egt from just the 16 sq. cm. exhaust housing on the stock turbo.
Second, the 370 HP injectors are well matched to our engines. Highway mileage will be similar but you may lose 1-2 mpg in town. The other marine injectors do not generally work as well for our 12-valveTurbo Diesels.
Third, after you work with and dyno some Turbo Diesels you will no longer say anything about the ease of hopping up a small block Chevy. It is far easier and cheaper to get very large power gains from the Cummins. People brag about 500 HP small block Chevies, but that is flywheel HP. Add 20% to the rear wheel HP numbers generally discussed for the Turbo Diesels, and compare costs. Then consider that the diesel will last far longer and is still a workhorse, not a garage queen.
Fourth, I wouldn't bother with an intake system yet. The stock airbox max'es out at about 550 HP, and I used the stock air intake horn at 800 HP.
These topics have been covered many times in the TDR, so I suggest you peruse back issues. Members can access issues online back to #44.