[vector1]

yeah, i thought about this after i posted, it is ran to the top of the header tank.

i guess low pressure or suction is considered to be from waterpump inlet to radiator tank side, and high pressure is after waterpump through block out thermostat to other radiator tank side.

the bottom of the header tank is connected to the low pressure side, so the line off the back of the manifold is connected to the top of the header tank.