GrimmSpeed Catted J-Pipe/Downpipe | 2015+ Subaru WRX (007103)


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304 Stainless Steel Catted J-Pipe/Downpipe for Subaru WRX 2015+ Manual

With the 2015 J-Pipe, the devil is truly in the details and the product development team here at GrimmSpeed has taken the time necessary to knock each of those details out of the park. As a result, what you see here is a meticulously engineered J-Pipe with an innovative flange design, single piece construction, excellent ground clearance and fitment with superb quality and craftsmanship.

Performance of the J-Pipe was verified on our 2015 WRX using the following method. Our tuned baseline run is the same run that we used in showing the boost control performance of the GrimmSpeed 3-Port Solenoid. We then installed the J-Pipe and retuned the car, using the exact same tuning methodology to ensure consistency. This ensured a real apples-to-apples comparison between the stock J-Pipe and the GrimmSpeed unit. The results showed a gain of 26.7whp (14.1%) and 19.8wtq (9.0%) and are displayed in the chart to the left. The percentage gains should be the focus here, as this particular dyno reads very low (stock baseline was 171). From a completely stock vehicle, users can expect a gain of around 45whp (27%) and 70wtq (41%) with the installation of the GrimmSpeed J-Pipe and custom tuning. The chart on the right shows this comparison.

Our engineers began by 3D scanning the OEM J-Pipe and vehicle underbody using our in-house FARO Arm. That data was used in CAD to design a pipe that fits perfectly within the tight underbody packaging on a 2015 WRX without sacrificing ground clearance. The 2015 WRX uses a series of OEM brackets to support the weight of the turbo and J-pipe, the most important of which bolts to the turbine outlet flange. Our engineers insisted on using thick 1/2" stainless steel flanges, but also knew that without a clever design, the very important OEM brackets would no longer line up. The GrimmSpeed flange design uses a CNC machined pocket that the OEM bracket sits in during installation, allowing the use of 1/2" thick flanges as well as the factory turbo support bracket! Finally, they worked tirelessly to design and manufacture a J-Pipe that could be bent from a single piece of tubing. This allows for more efficient manufacturing, less potential failure points and a product that fits perfectly each and every time.

Please Note: Grimmspeed has released the V2 revision of their 2015-2021 WRX J-Pipe! Their V2 J-Pipe includes a GESI catalytic converter and has undergone some tweaks and changes in order to mimic OEM placement and avoid throwing CELs. Check out the Grimmspeed V2 FA20 WRX J-Pipe here!


  • Innovative Turbo Flange Design - 1/2" thick while retaining all OEM brackets
  • One-Piece Tube - Ensures exact fitment, robust construction and ease of installation
  • Smooth 3.5" to 3" Transition - Matches turbine outlet size and then reduces quickly to maintain exhaust velocity
  • 100% Made in the USA - Manufactured right here in Minnesota
  • Optimized Tube Routing - Maximize ground clearance and minimize flow restriction without modifying suspension hardware, etc
  • Custom Stainless Turbo Studs - Replace the terrible OEM studs and nuts with these, machined specifically for use with 2015 WRX turbine outlet and our 1/2" flanges
  • Standard 3rd O2 Bung - Allows the future use of aftermarket sensors
  • Grounding Strap Mount - Retains all factory functionality
  • 300 Cell Metallic Substrate Catalytic Convertor (Catted Models Only) - Excellent balance of the reduced restriction of a 'race cat' without the stink of a 200 cell unit


  • 2015-2019 Subaru WRX Manual

What's In The Box?

  • 1x Welded J-Pipe Assembly
  • 1x GrimmSpeed Stainless MLS Turbo to J-Pipe Gasket
  • 1x GrimmSpeed Stainless MLS J-Pipe to Catback Gasket
  • 4x Stainless turbo studs w/ nuts
  • 2x Replacement catback bolts w/ nuts
  • 1x O2 Sensor Plug (plugs third O2 bung for future use)
  • 1x Grounding Strap Bolt (not pictured)
  • 2x GrimmSpeed License Plate Frames
  • 1x GrimmSpeed Sticker


  • Grimmspeed Limited Lifetime Warranty


  • Installation Video (linked above in image thumbnails)

Customer Reviews

Based on 38 reviews
Anthony Madrid
Great Downpipe

My WRX sounded way better with this downpipe, it was louder and deeper. It was produced and welded perfectly. It fit perfectly and was an easy install. Would definitely recommend to others.

Arturo Mendez
J-pipe w/stock exhaust

If you want more exhaust flow, more turbo spool this J-pipe can help get the job done. J-pipe with the stock exhaust has a nice tone to it. Almost like a beefed-up guy with soft voice. That is what you are going to get exhaust tone wise. You want to free up some ponies reduce some lag this j-pipe can help. Would you rather exhale through an inch straw, or would you rather exhale through a five-inch exhaust? I can't really explain how it sounds. It sounds does however sound throatier. More growl especially if you pair it with a cat-back. You do need a tune! The only hard part is removing the top right nut. And turbo bracket is a pain in the rear. Seriously, the only hard part is that stud and that ridiculous bracket.

Karlin Becker

The sound and power gained (after a tune of course) is amazing! Pretty easy install just slow for time incase you bust a turbo stud like I did!

Hunter Pappas
Sounds mean

I’m really glad I went with this j-pipe. Not extremely loud but def a lot louder and sounds really aggressive paired with my 3” single exit catback.

Sergio Pagano
amazing sound

installation was hell as one of my turbo studs snapped off. It's common for wrx's to be a pain with any downpipe installation. I recommend getting it somewhere to get it done professionally. The turbo sound out the exhaust is so loud and nice now. Exhaust is overall louder but with a more aggressive and nicer tone to it. Can't get over it