I have been chasing cooling issues in my system for years. I stumbled upon people doing this and it helping. I just replaced the radiator with a Griffin and it couldn't keep up with the cooling. They asked me to verify I was seeing good water flow through the radiator. I checked it without a thermostat and the flow was pretty bad with a mechanical pump and 1:1 ratio pulley. I drilled and tapped the hole and the flow was night and day. I could see the water rushing through the radiator. Now I am playing with thermostats and restrictors to get it tuned.