How do boy racers get their cars through MOTs?
To understand why the cars are so loud you have to have a basic understanding of how the “loud noise” actually helps. The loud noise of a “boy racer” is actually an aftermarket performance exhaust that has been installed. In all of today’s production cars manufacturers install mufflers to muffle sound and also catalytic converters to convert harmful exhaust gases to more eco friendly gases that also muffle sound. The downside to the sound dampening devices is that they restrict the flow of the exhaust. To get an idea of what this means, blow through a straw. Then bend or pinch the straw and try to blow through it. The increased pressure and blockup causes you to exert more force just to blow air through. The same gereral principal works with exhaust systems. When you free up an exhaust system with a straight through muffler and a high flow catalytic converter you are increasing the power output of the motor which makes the car faster. Even something as simple as a straight through muff
