This may be a bit off the line of thought here but in the Motocross world there is a company that makes aftermarket water pump impellers. Which are made to pump coolant more efficiently and more of it. Couldnt we take apart a normal L28 water pump and press on a better performing impeller and maybe make it to tighter tolerances to the front cover and have it tested to flow more efficiently. Maybe im off base but if it works so well for motorcycles why not for a car...