So how do these downpipes create so much horsepower? They allow the turbo to breathe better, and make better use of the power they are capable of making. For example, with an upgraded intake you are allowing the turbo to inhale large volumes of air, whereas the downpipe removes the restrictions and allows the turbo to exhale much better. This results in horsepower gains, torque gains, reduced turbo lag, and more than likely an increase in throttle response.
But like the intake, in some makes and models, you cannot bolt a downpipe or Y-pipe on and call it a day. Some cars like the Subaru WRX or Mitsubishi Evolution and the Nissan GTR require a tune to safely run a downpipe. Usually, with a Subaru, you can risk hitting fuel cut, so you would need some sort of Engine Management such as the COBB Accessport and one of their many available off the shelf maps will be available for users to load and drive safely.
If you drive a Subaru STI, you can choose options such as the divorced wastegate option, open bellmouth, and you can even get downpipes that come ceramic coated for extra protection against heat. And if you want to maximize the power of your car, check out our large selection of cat-back exhaust systems.Read Less