Here is a fused relay, this takes a signal from the in tank pump (converted to a low pressure lift pump) circuit, and activates power direct from the fusebox to the fuel pump.
At this point I'd used a certain gauge cable (seen above in blue), but got a bit scared reading posts suggesting stupidly high amp rated cables. So I switched to what I think is a sensible 27 amps rated cable for the high pressure Bosch 044 pump. Still need to bolt it properly, but I need another hand!
I'd bolted the pump somewhere sensible, and fixed the relay. I still have a bit more work done but nearly there.
Bit more cable tidying to do, and to connect the relay signal wire.