How would you know why things may or may not have to be moved

I havent had to move or relocate anything because of poor planning yet (except considering putting the turbo in the back was a bad idea

but I knew exactly what it would entail and what drawbacks it would have and due to my "good planning and mocking it up" the - "it wont do this or that well" hasnt been issue)
Things like weight distribution, and rule changes arent things you can compensate for with cardboard and mockups unfortunately either.
It needs to go in a certain place, so I dont run into core support rule crap, can fit a forward facing inlet turbo, gear driven supercharger, or an inline6 whihc is inherently a little longer. No one makes one like I want, so Ill likely end up making it, because I like making stuff work. Kinda like no one made a rear mount turbo kit thats worth $20, so I ended up making it