I sent my headers to JetHot, believe it was Texas. Took about three weeks before they were back in my hands, but I am in Hawaii.
Caution on tubing wrap. It will trap moisture, which leads to rust and corrosion. Okay for a track car where you'll be rewrapping after every meet. But I would not recommend them for a street vehicle.
And on your coolant system performance query.
Look Up evans cooling, Stuartcooling systms and Arrowheadradiators .. All in google how to increase automotive cooling system performance...
Think you will find some good info.