Scale Car Modelling

i have been doing an extensive researches on how air behaves in motion for my intake and exhaust design and came across Radial Momentum theory which basically says air that flow in conical shaped tube where the radius increases from inlet to outlet will have gradual pressure drop

this is in contrast with bernoulli's where when gas expands due to increased radius, pressure will increase. please take some time to read the link below, it really helps understanding how air works if u are...