Plenty of Subaru lovers install a GrimmSpeed steel downpipe in order to open up their performance potential. It is considered a “cornerstone” upgrade, the kind of modification meant to make a big difference in its influence. Exhaust restriction is something every driver has to contend with. But for those who need to go fast it can be a troubling issue. A GrimmSpeed steel downpipe goes a long way towards freeing up exhaust flow for extra power. The best part is that you do not have to use one alone. A GrimmSpeed steel downpipe mated with other Subaru exhaust parts can yield huge results.
Catalytic converters are intended to filter out harmful, bothersome fumes, not cause restriction. Yet in a stock Subaru, that is what they do. A Grimmspeed performance downpipe takes away this problem. By clearing out the stock catalytic converters, exhaust flow is no longer interfered with when exiting. The job of the Grimmspeed performance downpipe is to offer a wider and more direct route for air to travel through. Once in place, exhaust passes through the system with greater urgency and density. Horsepower picks up, torque is realized, and RPMs climb. Once installed, a Grimmspeed performance downpipe makes a difference right away.
One thing drivers notice about this part is its toughness. Grimmspeed purposely makes their Subaru aftermarket racing pipes thicker and more substantial than their competition. Even the flanges show more density. The flanges on their Subaru aftermarket racing pipes measure in at a 1/2” thick. This is to allow for a tight seal and also to prevent any cracks or fractures. And of course, Subaru aftermarket racing pipes come made of T-304 stainless steel. The 3” diameter tubing is mandrel-bent for precision angling. This method also enables the Subaru aftermarket racing pipe to display better structural integrity once mated to your exhaust.
You have a choice when it comes to design. If you would still like to be kind to the environment, an Impreza downpipe can come “catted” with a 300 cell count catalyst supported by a metal substrate. However, even with the cat, you will still need to exercise caution. Certain local emissions laws may prohibit usage of a Grimmspeed Subaru pipe on residential streets. It is recommended to only use this part in sanctioned competition.