copper heater lines - info

hey all - just a heads up for anyone considering replacing the heater lines on the closed cooling system with copper. I did this last weekend and the coolant shot into the overflow tank too hard, it foamed up real bad. the reason is that in the OEM metal tee, there is just a small hole (I would guess less than 1/8 inch going from the main line (from engine to heater core) where the expansion tank line is spliced on. it looks like it is about 1/2" tubing all the way through the tee but it isn't. so if you do the copper tubing mod it becomes a bit more complicated as you have to have a small restrictive hole going to the expansion tank.