..well, for 450 HP you "should" have
A lift pump with a filter
A built CP3
A SunCoast transmission (ok, I'm partial to SunCoast) ...A built trans with Converter.
A trans cooler from Mike L.
There are several boxes/systems to choose from for your wants. However, I would read as much as possible on this. Several power-adders work and can attain the power but they do not do it in a good way.
.......and a bit reserved. Heat is your main enemy. (IMHO) The Duramax can run all day long @ 1300 degrees EGT, 210 engine and 200 trans temp.
Just like your Dodge, hot rodding a cold drivetrain/engine is never good. Even worse is shutting down a hot system, mainly the turbo.
$.02