Product Details
Subaru WRX STI 2015, Downpipe by GrimmSpeed®. 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 their single high-flow unit will dramatically improve performance potential while maintaining the use of a catalytic converter. Within their complete lineup of downpipes, you have the option to add a high-flow, 300 cell catalytic converter, fully machined and contoured flanges with beautiful brushed tubes and black ceramic coating. Whether you're racing time attack or to work and back, GrimmSpeed got the perfect downpipe for you.
Notes
- Once you have added the downpipe to your vehicle, it must be tuned. Replacing your factory catalytic converter sometimes causes a 'cat converter efficiency’ check engine light. You can either use tuning to delete this CEL or you can use a mechanical fix.
Specifications
| Main Piping Diameter: 3.00" |
| Quantity: 1 Piece |
Features
- Proudly made in the USA - Design, Materials and Fabrication
- Innovative 3-D Contour Flange (Limited models only)
- FARO™ Arm Designed - We are at the leading edge of new product design hardware
- Flanges Fully CNC Machined (Limited models only)
- O2 Bungs for factory sensor and aftermarket wideband AFR
- Divorced Wastegate for Optimal flow
- High-flow, 300 cell, metallic substrate catalytic converter
- Expertly made from sturdy materials
- Made to help enhance the performance of your vehicle
- Perfect solution for racing and high-performance engine applications
Design
GrimmSpeed use 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 we've added will save you time and money when you decide to use a wideband O2 sensor/gauge in the future. As engineers and enthusiasts, they take great pride in the work that they put into their design process and it shows in the finished product.
Materials
Material selection is a very important, but often overlooked, part of an aftermarket exhaust system. The tubing they chose is a thick 3in, 16ga 304L Stainless Steel tubing and their meaty 1/2" flanges will resist warping and leaks in even the most extreme environments. Stainless steel, particularly 300-series alloys, have terrific durability and corrosion resistance but are still quite cost-effective for fabrication of this type. Lower grade alloys (400 series, for example) may be more prone to corrosion over time, reducing the life and beauty of your parts while higher grade alloys introduce unnecessary cost. All flanges use a fully-machined bolt pattern to ensure very tight tolerances and flawless fitment. Each tube is CNC mandrel bent and CNC laser cut for perfectly repetitive fitment and accuracy. The catalytic convertor that we've selected is custom sized and utilizes a metallic substrate for increased effectiveness, higher flow and better durability than other, lesser units. They selected a 300 cell count mantel for a perfect compromise of performance and function.
Fabrication
This is where the rubber meets the road. Every single 02-07 downpipe is welded in the exact same master fixture. Their competitors build their welding fixtures around a single OEM downpipe. They build their fixtures to the average (found using the CAD data mentioned above) of a number of OEM downpipes and turbo/catback flange locations. They periodically re-check their fixtures using their FARO arm to ensure that heavy use and heat cycling don't affect their accuracy. Each downpipe is TIG welded by one of their two expert welders, Chuck and Andrew. Don't be fooled by shiny immitations where a robitic TIG pass has been made over a wire-fed MIG weld; real TIG welding takes the skilled hand of a true craftsman. Chuck and Andrew take the structural integrity and beauty of their work very seriously and when you handle your new GrimmSpeed downpipe, you'll know it.
GrimmSpeed® was founded in 2006 to provide customers with innovative and highly engineered aftermarket products. In short, they are a small group of highly dedicated car nuts who work in Minneapolis, Minnesota. GrimmSpeed® bread and butter started out anything Subaru. However, after growing GrimmSpeed® team and engineering they started developing products for: Mitsubishi, MazdaSpeed, and Hyundai markets. GrimmSpeed® are a true garage start-up and they have been lucky enough over the years to be able to turn it into exactly the business I had dreamed....probably a lot more actually. GrimmSpeed® have a wide breadth of expertise consisting of exhaust design, gaskets, pullies, phenolic spacers, porting and polishing, boost controllers, and many more.