Planning?

I want to take measurements of my engine bay to figure out where I can put stuff. I am thinking of getting a piece of graph paper, and sketching the engine onto there. That way I can plan out where I am going to put all my piping and turbo and how much room I will have, things like that. Sound like a good plan?

Are the dimensions of the turbos on the manufacturer’s websites?

Also, do I have to buy a premade manifold? Does anyone here have experience with a custom manifold?