OK if your looking to size a single ecm pump find the ft of head in all 4 systems. Take the highest ft hd and used that number. Now you need a pump that will do 52-60 gpm at that amount of ft hd. Make sure you size the manifolds and headers so it doesn't add much ft hd. If your going to run a delta p ecm pump you can over size it a little I think to be safe.