Originally Posted by Boudreaux

Rob, on my 06 the return line goes behind the block and ties in to another line and seems to make a "loop" for lack of a better word, so to me that's a clue the coolant serves another purpose. I'm not saying Do Not do the mod,I'm more comfortable with a 3 valve, 2 tee bypass where the coolant continues flowing but not thru the heater core. Hope this helps.

Boudreaux