Now you have enlightened me! The 3core is a much tighter airflow core than I have seen in oem rad's. You may have touched on the issue cause I remeber my valiant being transparent as in you could see through the rad almost I do know the tubes were spaced farther apart as to let air flow through easier. I'm going to find one of the 2core wide tube type rad I think you have touched on the issue I'm going to do a smoke test on the rad that is in it and one on a wider core oem rad and see if that is where my cfm's are going too . Thanks for your thoughts I'm going to try that today and will get back with you.