Pulse Chamber - Explanation
Since the first-ever gas engine was invented in 1861, there has been a demand for waste gases (Exhaust) to be safely redirected and regulate noise levels. Leap to the 1970s with mass production of gasoline-powered vehicles, modestly priced, and easy to maintain grew in mass numbers. Managing air quality was becoming obvious and apparent, and the solution was the first catalytic converter mandated on all vehicles in 1975. These were single "pancake style" multi-level core resulting in very little flow with a lot of backpressure.
1999 was a game changer for the automotive industry, with computer technology managing fuel trims, manufacturers updated to a single monolithic Cat. per bank with an OBDII Monitoring System. (This style system is found on all current vehicles.) This indirectly created a detrimental droning effect that companies still struggle to understand. The automotive manufacturers' "fit-all" they found was to restrict the exhaust to such an extreme amount, that the droning stopped and kept the interior quiet. This added restrictions on the stock systems, and reduced performance, and mileage.
With the changes during these times to gas-powered trucks, in particular. The aftermarket "standard " fixes were tested. There was certainly a proven product pre-1999. The ole H-pipe during the testing, had no positive effect on the drone, while the H-pipe system resulted in a loss of power to the rear wheels with the exhaust bouncing in between banks. Next up would be an "X-pipe". These had very good results previously in muscle cars where the exhaust lengths were relatively balanced. That technology was applied to the Truck Exhaust System and the problems simply revealed themselves. We constantly tested several different shapes, hole sizes, hole shape, tubing sizes, and figures, but nothing was working correctly with exhaust pulses.
What is an Exhaust Pulse? When the exhaust valve opens inside the combustion chamber to exchange the expelled oxygen now Co2 gases. There is a large volume of gases bunched together traveling pushed through the exhaust.
8 cylinders x 2500 RPMs = 20,000 Exhaust Pulses
In designing the Patented Pulse Chamber, both the X-pipe and H-pipe's biggest errors were not forcing the exhaust pulses to enter a single expansion chamber to equalize & properly mix the pulses. Every exhaust pulse travels different lengths in the system which produces a different pulse size. MPI's pulse chamber allows the pulses to expand and mix all 8 different exhaust pulses to create the same size and sound exhaust pulses.
Why does a very restrictive system, not drone? What the factory system found, is when the unbalanced pulses travel 18-20 inches down a tube a system will drone. By adding large amounts of restriction you stack all those exhaust pulses limiting their movement and stopping the drone effect.
Patent - 11713700