Grimmspeed - Downpipe Catted (02-07 WRX / 04-07 STi / 04-08 Forester XT)
   Quick Product Info
Brand: Grimmspeed
Part #: F-GRM-007082
Catalytic Converter: Yes
Coating: No
Gaskets Included: Yes (a $40 USD Value)
Hardware Inlcuded: Yes
Material: 304 Stainless Steel
Mouth Design: Divorced Wastegate
Piping ID: 3.0 in
   Confirmed Applications
2004-2007 Subaru STi
2002-2007 Subaru WRX
2004-2008 Subaru Forester XT
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Product Details

A downpipe is one of the first modifications that should be done on your car, as the OEM downpipe contains two very restrictive catalytic converters. Replacing these with GrimmSpeed single high-flow unit will dramatically improve performance potential while maintaining the use of a catalytic converter.

Grimmspeed uses 3D scans of 10-15 OEM downpipes to identify the variances within stock parts and ensure that their fitment is perfect across the board. They then pull those scans in 3D CAD and design their downpipe with flange locations, transmission tab locations, O2 bung locations, firewall clearances and material selection in mind. Bend locations, tube lengths and divorced wastegate re-entry point are all checked for healthy flow using CFD (computational fluid dynamics) simulations in CAD. With even the largest stock location turbine outlets utilizing factory exhaust gaskets, they used a reduction process to smoothly transition from the 2.5" turbine outlet to their 3" downpipe material. The outlet of the downpipe has a standard 3", 2-bolt flange that will mate up with most aftermarket catback exhaust systems and the secondary O2 bung that they've added will save you time and money when you decide to use a wideband O2 sensor/gauge in the future.