I'll rephrase. IMO they both transfer heat but its too little too late to provide any benefit. The cylinder head (of course) is the heat source and I find convection thru the intake runners happens a whole lot faster than it takes coolant to warm up or push exhaust thru a straw size tube. Most of us are familar with the symptoms of a stuck open heat riser/too much manifold heat so I believe like the stock system heat needs to shut down as soon as the manifold warms. So far it's only speculation but I have a feeling the glow plug approach may solve this issue very effectively.
