I have not seen this mentioned anywhere else, but the Champion 3-core radiator has a much larger capacity than the stock Fiero radiator. Almost 1.5 gallons more. It would seem that more coolant would be better for cooling, that more weight in the front would not hurt, and that more coolant flowing through the radiator would give the fluid more time to cool.
Does anyone know?
I'm also wondering if the additional coolant necessitates additional strain on the water pump.