Quote:
Originally Posted by bmwman528e
Correct. Also keeping it quiet around town and if I'm down on power to 300rwhp out of boost with factory x5 mufflers it will still be plenty fast and once the car starts to build boost the cutouts open thus me having no restriction at all. I still haven't decided that I'm doing this exact exhaust setup but it's definitely one of my top choices.
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Vacuum is the greatest when the engine is idling. As RPMs increase vacuum decreases. Vacuum varies somewhat by engine, condition of engine and where the hose is connected so it would be very difficult to offer anything but vehicle specific models. Do you have a link to cutouts that have no switch?
Cutouts reduce restriction but do not eliminate it. The engine is restricted by the stock exhaust manifolds, by the size of the exhaust pipes and by the cats that should be before the cutouts. Headers are always a much better performance option.