The Homologation of the different exhaust systems parts (silencers and catalytic converters) is a process of comparison between the Original Equipment part, and the part that we want to homologate for the Aftermarket. This process will guarantee to the end consumer, and the installer, that the unit that he will be installing is equal in back-pressure and noise levels in comparison to the one designed by the vehicle manufacturer.
This fact will guarantee to us that installing an homologated exhaust system (silencer or catalytic converter) will always maintain vehicle´s performance level.
Its consumption level will be equivalent to one equipped with an original part.
It is important to note that the installation of non-homologated silencers, or catalytic converters, is prohibited, and is considered an illegal activity within the European Community area, as well as fitting non-homologated tires, or laminated glass for car windows. Non-fulfillment of these guidelines will be penalized by the local authorities.
We need to have in mind that the main characteristic of a homologated Muffler, or catalytic converter, is that, the exhaust or catalytic converter has passed some test to ensure that the back-pressure is the right one for the optimum performance of the engine.
On the other hand, any variation in the back-pressure level (independently of whether it is more or less) produces a leakage of unburned hydrocarbons (HC) and oxygen constantly during the valve overlap period. This HC and oxygen leakage will end in the catalytic converter´s monolith surface, which normally works at over 500 ºC making the HC auto-ignite. When that happens, the HC burns and generates 1,850ºC, which produces small fusion areas over the catalytic converter monolith, damaging it.
Maintaining this situation will end up melting the monolith of the catalytic converter, and producing the characteristic knocking noise under the vehicle.
Due to the fact that in a back-pressure problem we lose petrol, and oxygen constantly, this petrol is not burned in the combustion chamber, increasing the consumption and decreasing the power of the vehicle.
At the same time, and due to the fact that the catalytic converter is receiving higher amounts of pollutants (HC), due to the leakage produced by the back-pressure problem, not all the gases will be transformed into non harmful gases, producing an increase of pollutants emitted from the rear pipe, and increasing damage to the environment, and human health.
In newer vehicles (after EURO IV), the use of non-homologated exhaust systems can cause premature failures, and serious damage to new, expensive and sophisticated systems such as DPF, SCR, Slip Catalytic converters, NOx sensors, wide-band lambda sensors, etc...).