Right now for me, I don't think those tests mean ANYTHING...I'm still thinking about it. I still think more flow only slightly increases the performance of the radiator...I don't want to type up the explanation, takes too long. I'll have my mom bring some Y fittings home...I don't have any and the hardware store doesn't sell them for some damn reason, then I'll test it for myself. But definitely, parallel should give the loop overall higher flow.