Originally Posted by timruger1
2. Most of these trucks have small HP motors like a cat C7 or DT446. Can i dial these up to 300ish HP or am I starting over with a new motor?
To answer your first question:
You can dial it up beyond all sensibility until it blows smoke [aka 'unburnt fuel']. However, longevity is limited by the capacity of the rest of the drivetrain. The clutch has an opinion. The transmission has an opinion. The U-joints have an opinion.
At what point does additional torque over-power the frame and brakes? I'm not an engineer, I wouldn't know.
To answer your second question:
A larger engine / transmission / frame / brakes is usually a good idea. How much safety can you afford?