It was running at 210 but I think part of it too was a faulty mr gasket hi performance thermostat. But even when I had a oem themostat it ran at almost 200. So I'd say it dropped it 30 degrees.
As far as coolant being necessary i've been told it's not.... By a few other people.
I actually spoke to Martin at Justice Bros (heck of a nice and helpful guy) and he said the same. He actually spent about 10 mins on the phone with me going over my setup and then suggested the products and what to run them with.