What are your bus specs? Size, engine, trans?
A torque plate is inside the fuel injector pump. A few things need to be considered and planned for before modifying a Diesel engines performance.
My bus has an 8.3L Cummins with Allison MT643 trans. A modest 85 hp upgrade has made all the difference in the world with respect to power on climbs and towing. The bus used to look at a hill and slow down.
I am able to monitor boost and EGT so I don't start damaging things internally in the engine. More details of you want but there is a ton of info online on this subject.