The Internet is a series of Tubes. (or so we have heard....) And so is your car. Think of air as the delicious beverage and the straw as the intake, turbo, and exhaust system of your car. From a thermodynamics perspective, it's a pump. Grab a straw. Cover up the end of it and try to breath. That is the stock downpipe as more boost is generated. 

The Krona 3" downpipe, aside from being a beautifully crafted stainless steel work of TIG welding, provides a bigger straw. As Your Swede requests more boost, the exhaust turbine on your turbo begins to stall as the hot gases in the turbo make it more difficult to turn the compressor wheel. This downpipe lets more exhaust evacuate from the system faster, making more room for fresh, boost creating exhaust gases. Get those gases flowing fellow Swedes!

Some Modification required for cars with automatic transmission. Fits all TD-04 and GT17 turbos on 9-5s with a stock manifold.

Krona 9-5 Down Pipe