it's because horsepower = (torque x revs) / 5252
so it's 1-to-1 when the revs match the equation denominator
the cross over point is different if you use kW&Nm, or kW&ftLbs, or PS&kg.m, or whatever variation...
just a thought here
wouldn't the big 'ol metal clamped filters that are exposed to the engine bay that people fit on top on carby powered V8s be in the same boat 'flamability' wise as pod filters? hmmm...