There are a lot of reasons why it's illegal, but that being said...
The weirdest thing is the heat distortion and smoke distracts you. When the engine rocks during acceleration, the stack moves a lot, so don't clamp it too tight. Rain goes in it, and when you start it up, it splatters your truck with black globs of oily carbon.
I like hotrodding, but the hood stack is pretty much a bad idea for real driving.
I just laid out the hood with grease pencil and cut it with a jigsaw with fine blade. Put blue tape everywhere or the saw will scratch the paint up pretty good. Sand off all the sharp edges, and get some black trim band from McMaster for 1/16" sheetmetal. You will have to cut an egg shape to clear the hood when you lift it up. Give it 1" clearance in all directions.