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Originally Posted by FAR888  Question is: Are twin exhaust pipes an aesthetic addition to the W164 ML350 or do they actually serve a technical purpose? |
Mostly aesthetic. If you examine most factory model changes that add dual exhaust you'll find the actual throughput of the system does not have a material change. There is usually a constriction added in the chain or it is not a true dual system but merely a cat- or exhaust-back dual.
Making any change to a modern stock vehicle results in some negative effects. In the case of exhaust systems when you open it up you are modifying the power curve. It does _NOT_ result in an across-the-board increase in power. What it does it drop the power, often dramatically, in the lower RPMs while increasing the power slightly in the higher RPMs.
Now, if you spend all of your time with the engine higher than 4,000 RPMs then you'll see a power increase. But since nobody does that in normal driving what 99.99% of the population will see is an actual decrease in power. But it will sound louder, they'll think it will look better, and they'll never want to admit that they got ripped off <g>.