Have you guys seen the engine bay of classic custom trucks in the US? something like these

http://classictrucks.com/features/0407cl_55chev/

Check out the fire walls and the side wheel wells how clean and smooth. How do they make it so clean? I know that these things are assemble with crate motors but where do they hide all the wires and hoses? Or does it come with a separate sheet of metal to cover everything that's bolted on the firewall.