There is a difference between an Impreza catted downpipe and other exhaust system upgrades. Some modifications are intended to simply open up airflow for a bigger boost. You may get added punch using an Impreza catted downpipe, but you will also experience an increase in overall exhaust efficiency. Air will flow easier through the system, allowing the proper exchange of gases without emitting a mass of them into the atmosphere. For drivers who are interested in upping performance while still remaining cognizant of the environment, an Impreza catted downpipe can be an important addition to any sport compact profile.
When exhaust gets filtered through the stock catalytic converters it holds up the flow. That is because OEM cats are restrictive due to their design and tubing diameter. A GrimmSpeed Impreza downpipe swoops in to free the exhaust pattern. Instead of a narrow exit path, the outlet sports a wide 3” diameter. Exhaust is escorted out quickly through the GrimmSpeed Impreza downpipe, unlocking hidden performance gains. Being that it also has a catalyst, it will still filter noxious gases, just without being tied up in the process.
The key is that the GrimmSpeed Impreza downpipe uses a 300 cell count mantel with a metal substrate. Given the design, when thick, dirty fumes reach the converter they are passed through filtration without hindering flow direction. However, like most aftermarket down pipes, this part is not street legal. Removing the factory cat is against most state emissions guidelines. Operating a GrimmSpeed Impreza downpipe is recommended for racing purposes only.
T-304 stainless steel is employed for both durability and effectiveness. GrimmSpeed manufactures each Subaru Impreza downpipe to be extra sturdy. The tubing is bent using a mandrel, promoting a precise angle that sustains strength without tapering. Perhaps as importantly, Subaru Impreza downpipes showcase 1/2” flanges that are CNC-machined on all three sides. This not only encourages a tight seal, but it also makes mating to the custom performance exhaust effortless.
You can find this part available for 2002-2007 Impreza performance models. Whether it is for a WRX turbo exhaust or to compliment your STI’s configuration, this Subaru Impreza downpipe will provide an accurate OEM-like fitment. A wideband O2 bung is included, as well, so you will not have to seek out a shop and spend extra time and money.