Originally Posted by c32AMG-DTM
I believe that to, in fact, be an incorrect statement. The cross-section area of the tube would be pi*r^2. 3.14 * 1.25 * 1.25 = 4.91 inches of area. So, duals would be 9.8125" of total area. By comparison, 3.14 * 2.5 * 2.5 = 19.625" of total area. In conclusion, the single 5" exhaust tube would flow WAY more than two 2.5" exhaust tubes.
Hagen-Poiseuille states that airflow through a tube is the fourth power of radius. This means that a 5" exhaust would flow 8x more gas than 2 2.5" exhaust tubes.
Don't ask me how to pronounce Poiseuille, I have no idea.