RE: Best Pressure Tap Location On Tuned Pipe?
In theory, the widest part of the exhaust system will provide the greatest pressure Bernoulli says so and he's smart!
However...
Since the exit area of the pipe is smaller than the inlet area, the average pressure inside the exhaust system will always be greater than the ambient pressure outside so you can actually put the tap *anywhere* and still see a positive *overall* pressure.
I've run taps on the manifold and on the pipe both work.
A pressure-tap on the manifold/header *will* fluctuate from positive pressure to negative pressure. However, the *average* of those two variations will always be positive so the tank will still pressurize.