Do you have a link for the kit?
I am adding a coolant filter to my truck, see sig, and will be taking coolant from the plug by #6, to increase the flow to the rear of the block. The filter is only 2GPM, but its better than nothing!!
Not sure how much it helps the flow but, when I installed a coolant filter on my truck I moved the heater supply to the plug by number 6. My coolant filter supply is where the heater supply used to be.