Unlocking extra performance is what a WRX custom downpipe is meant for. If you are trying to put together a full racing package you need to upgrade the exhaust system. Throwing in a WRX custom downpipe is usually the first order of business for competitive racers. Part of that is due to the stock setup. Subaru did not include a performance exhaust with their turbo models. It is up to the driver to put the proper modifications in place. A WRX custom downpipe takes care of eliminating a large portion of restriction holding you back on race day.
When exhaust is able to move freer, your car’s performance instantly improves. The goal of a Perrin downpipe is to provide an easier flow route to the turbo. The stock pipe is thin, narrow, and not designed for high performance. When tubing is narrow, exhaust gases cannot stream through it very easily. A Perrin downpipe releases the back pressure this causes. Once the airflow is opened up, the engine’s boosting capability is no longer as hindered. The result is more horsepower and torque. Perrin downpipes can add as much as 20 extra HP to your car. When you overhaul your Subaru performance exhaust, you will need one of these to complete the package.
One thing to note is that a turbo down pipe is not intended for usage on residential roads. The reason for this is due to the removal of OEM catalytic converters, which are present on the original part. Cat converters are responsible for filtering exhaust and removing potent fumes. Even if you were to purchase a catted Perrin downpipe, it would still be illegal. That is why this product is engineered for competition use only. You can use a turbo down pipe on any race track or off-road course (as long as it is sanctioned for competition).
Perrin carefully makes all of their Subaru racing parts out of stainless steel. Each turbo down pipe is engineered according to vehicle specs and mandrel-bent for an accurate fit and effectiveness. The flanges are well-known for their toughness. Measuring in at 1/2” thick and CNC machined, they are much stronger than the OEM. All WRX/STI Perrin pipes come with hardware and instructions.