Catted Downpipe - 08-14 WRX / 08-21 STI / 05-09 LGT

Exhaust Adapter Add-On

Current stock: 0

It appears that you’re not the only one with excellent taste in premium automotive components! Unfortunately, the standard non-coated version is temporarily out of stock, however should become available soon. You can still place your order and be put in a queue; the item will be shipped ASAP. Please contact our customer service via email or phone (612-379-0000) with questions, or check for availability with our retailers, thanks!

USA's Finest Downpipe.

  • 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
  • O2 Bungs for factory sensor and aftermarket wideband AFR
  • Divorced Wastegate for Optimal flow
  • High-flow, 300 cell, metallic substrate catalytic converter
  • GrimmSpeed Gaskets Included - A $40 Value!

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 our single high-flow unit will dramatically improve performance potential while maintaining the use of a catalytic converter. Within our complete lineup of downpipes, you have the option to add a high-flow, 300 cell catalytic converter, fully machined and contoured flanges and black ceramic coating. Whether you're racing time attack or to work and back, we've got the perfect downpipe for you.



We use 3D scans of 10-15 OEM downpipes to identify the variances within stock parts and ensure that our fitment is perfect across the board. We then pull those scans in 3D CAD and design our 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, we used a reduction process to smoothly transition from the 2.5" turbine outlet to our 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, we take great pride in the work that we put into our design process and it shows in the finished product.



Material selection is a very important, but often overlooked, part of an aftermarket exhaust system. The tubing we chose is a thick 3in, 16ga 304L Stainless Steel tubing and our 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. We selected a 300 cell count mantel for a perfect compromise of performance and function.



This is where the rubber meets the road. Every single 02-07 downpipe is welded in the exact same master fixture. Our competitors build their welding fixtures around a single OEM downpipe. We build our fixtures to the average (found using the CAD data mentioned above) of a number of OEM downpipes and turbo/catback flange locations. We periodically re-check our fixtures using our FARO arm to ensure that heavy use and heat cycling don't affect their accuracy. Each downpipe is TIG welded by one of our expert welders. Don't be fooled by shiny imitations where a robotic TIG pass has been made over a wire-fed MIG weld; real TIG welding takes the skilled hand of a true craftsman. We take the structural integrity and beauty of our work very seriously and when you handle your new GrimmSpeed downpipe, you'll know it.

Limited Features


For those looking to take the finest downpipe one step further and wring out every last ounce of performance, we offer our 'Limited' line of downpipes. Limited downpipes use flanges made of the very same 1/2" 304L Stainless material, but with recesses for each tube as well as a beautiful 3D contour to smoothly transition the irregular shape of your internal wastegate outlet into our divorced tube for tighter boost control. Limited downpipes also come in a ceramic thermal coated version which are some of the best downpipes you can buy for your Subaru.

NOTE: Once you have added our downpipe to your vehicle, you 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. GrimmSpeed aftermarket downpipes modify OEM emissions control devices and are intended only for off-road racing applications.


  • 2008-2014 WRX
  • 2008-2021 STI
  • 2005-2009 Legacy GT / Outback XT (Manual Trans Only)
  • 2009-2013 Forester XT

Install Guide

GrimmSpeed Catted Divorced Downpipe Install Guide:

LEGACY GT/VF40, Outback XT/VF46 ADJUSTMENT GUIDE: You will need to slightly adjust the divider tab to fit a VF40/46 turbo. It's a very simple process, but please contact our customer service representatives if you have any questions.

12 Reviews

Wesley Kerr 27th Aug 2020

GS Limited downpipe

Awesome quality, beautiful finish on the limited downpipe!

Patrick 9th Sep 2019

Easy install, increases power/flow, better sound

Car: 2018 Subaru WRX/STi Exhaust Set-up: GrimmSpeed Limited-Catted Divorced Downpipe paired with Greddy RS Race (Single-exit, non-resonated) Other modifications: Cobb Cold Air Intake, GrimmSpeed Electronic Boost Controller, Crawford AOS V3, Yimi-sports Dyno-tuned Fitment: No doubt, this fits perfectly. I don't think there is any other way to describe perfect fitment. If you encounter any issues, then the installer is the problem. Performance: In comparison to driving with a stock STi downpipe, you can definitely feel a smoother airflow with the GS Limited-Catted Divorced (GSLCD) downpipe as the piping is significantly bigger in diameter and has less restriction due to eliminating 1 of the 2 catalytic converter in the stock setup. This set-up is also paired with a GS Electronic Boost Controller (EBCS) to prevent over-boosting (upon tune). Additionally, the "Divorced" setup will also prevent over-boosting which I really like so I can increase power in the car while somewhat maintaining reliability by not over-boosting. Sound: My setup is loud as it is with a stock downpipe, but adding an after-market downpipe usually gives an expectation of significantly increasing the volume. This is not the case with the GSLCD down pipe. The volume of the car noticeably increased, but not significantly which is what I truly love about this downpipe. There are two major differences that I noticed when I upgraded my down pipe: 1) Gives my car a "growling" sound when I hit about 4k rpm which I think is really loud, but cool. I mean.. what would you expect at 4k rpm? 2) Creates more turbo spool (whooshing sound) Overall, really great downpipe. From welding details to performance upgrade, GS Limited-Catted Divorced Downpipe is exactly the downpipe I was looking for and will recommend to my friends.

Add a Review