Two thoughts come to my mind. First, splitting the exhaust is to improve the flow out of the engine. How one does that might make some difference...but not much, I think. And second I agree that both a heat rise pipe and coolant under the intake are somewhat too little and too late. The question I would want answered is how much better if any are the aftermarket split headers than a well made split stock exhaust manifold? If there is little to no difference flow wise then it would seem that modified stock would get the most with the least as it were. The Fenton type do look good but if there is no gain and little advantage cool won't make you run stronger.
