I run dual heat, i.e. taking exhaust off each header. I tried single heat and determined the bottom of the intake manifold wasn't getting any considerable heat to benefit it's addition. Dual heat produced heat to the intake but no where near the stock single carb factory setup does.
Tom Langdon recommends piping heated coolant through the intakes heat chamber and will do his best to educate you to it's benefit over exhaust heat. The main drawback being the complexity over exhaust heat. He sells a kit for it if interested.
I opted to keep mine exhaust heated but have yet to run it on the road. all my tests are on a 235 on a run stand.
