Quote:
quote:Originally posted by Rolo
You would sacrifice some low-end (RPM) performance for high-end performance. A larger exhaust offers too little or no resistance at the low-end, forfeiting the Bernoulli effect (resistance = velocity, cf. a garden hose) and the Venturi effect at the intake; however, with more exhaust moving at the high-end, you gain those effects back without the overbearing restrictiveness of a smaller pipe.
It is an either-or situation, and you choose based on your application, same concept as a 4-to-1 header versus a 4-2-2 (tri-Y) header.
Now, if someone could make an adaptable variable width exhaust...ka-ching!
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Actually, in the case of Turbos (and for everything fuel injected) - there is no such thing as too little backpressure. That is something held over from the carburated days. So go BIG, especially in a Turbo - because the turbo spools up faster with less restriction and needs less wastegate up top to make the same boost. Backpressure costs horsepower and response, which is why an exhaust is one of the first things you should change on a turbo car.
That's why my race pipe is only 2.25" and pulls like you wouldn't believe. Put the cat back in, and - blah. But clean air is the name of the game right?