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3" Downpipe Adapter - Aftermarket DP>OEM Subaru Catback

  • GrimmSpeed Subaru 3" Downpipe Adapter
  • GrimmSpeed Subaru 3" Downpipe Adapter
  • GrimmSpeed Subaru 3" Downpipe Adapter
  • GrimmSpeed Subaru 3" Downpipe Adapter
  • GrimmSpeed Subaru 3" Downpipe Adapter
  • GrimmSpeed Subaru 3" Downpipe Adapter
  • GrimmSpeed Subaru 3" Downpipe Adapter
  • GrimmSpeed Subaru 3" Downpipe Adapter

Have questions about fitment or applications? Contact Us

Product Description

 Kill that exhaust leak for GOOD!

GrimmSpeed Subaru 3 in. Downpipe Adpater
  • Flared Adapter Transition!
    (Creates a smooth transition from your 3" downpipe to your OEM midpipe)

  • Flanged for OEM Donut Gasket

  • Indestructible Steel CNC Laser cut construction 

  • Simple bolt on installation.
    (With bolts included)

  • Will Not obstruct exhaust flow like other adapters.
    (Flared end guarantees smooth exhaust flow)


 Exhaust leaks seem to be an all-too-common issue with most modded Subarus. They tend to spring up out of nowhere and cause hours of troubleshooting headaches. The most guaranteed leak you will get though is if you run an aftermarket 3" downpipe to an OEM or OEM like 2.5" Exhaust. Compare our adapter to the competition and you will immediatly see why we offer the best solution to finally end that pesky leak.

Cut from Steel and hand welded these pieces were born tough. With the ability to work with both flat style gaskets AND donut gaskets they cannot be matched. If that wasn't enough we flared out one end to just shy of 3" so that unlike the competitors, our adapter will not block flow! 

A Final solution to pesky problems, it's what you can expect from GrimmSpeed™


NOTE: GrimmSpeed 3in. Gasket and OEM Subaru Donut Gasket SOLD SEPARATELY

Fitment Note: Adapter is only inteded to be used for connecting aftermarket 3in Downpipe to OEM style catback. It can not be done in reverse.

Product Videos

GrimmSpeed 3in. Downpipe Adapter Install Video (05:05)
  • GrimmSpeed 3in...
  • GrimmSpeed 3" ...

Product Reviews

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Product Reviews

Showing reviews 1-10 of 12 | Next

  1. No more leaks

    Posted by JKD

    I needed to stop an exhaust leak and this adapter sealed it nicely. My J-pipe isn't from Grimmspeed, but it works just fine. I bought it with the thicker 3" gasket and donut gasket. Now I have proper boost pressure.

  2. Great product

    Posted by Adrian Calderon

    Great quality part and all hardware was included. No fitment issues whatsoever. Always a pleasure doing business with you.

  3. Excellent Choice...

    Posted by Jermus

    I recently purchased a 2nd one. The first one I gave to my brother along with a my stock STI exhaust to fit up to his FXT w/downpipe. It was still in great shape and installed perfectly. The new one I got was fresh and well constructed just like the first. Price is right, quality is great, service is 2nd to none, and I have another GrimmSpeed sticker to add to the collection. :D

  4. I like it

    Posted by Anthony Boni

    It's a great adapter. Makes a good seal from a 3" downpipe to a 2.5" stock exhaust. Just make sure to also order the OEM donut seal.

  5. Great Fitment, easy to install

    Posted by Steve

    I'm planning on keeping the stock cat back for at least the next few months so this piece was a must. Installation is a breeze while doing the downpipe. Great fitment, no leaks. Included hardware and gasket was much appreciated.

  6. Perfect solution!

    Posted by Jon

    I purchased the Grimmspeed downpipe and I have an SPT exhaust. I love the exhaust but not the 2.5" reduction at the flange. Still I want to keep the exhaust.

    Enter the Grimmspeed downpipe adapter. It does what is stated and is the best resolution for the 2.5" issue some of us face.

    top quality welds and plated as well. Another great product that is simple to use.

  7. Great Option.

    Posted by Andrew B.

    This kit allowed for a clean installation of the catted jpipe while also allowing me to maintain my stock CBE for the time being for idle/around town stealth and still get 95% of the power from the jpipe.

  8. Worked perfectly! Great fitment!

    Posted by Dan

    Sealed up my ebay downpipe to my stock catback with zero leakage. I used the oem donut and the shoddy ebay graphite gasket and it sealed and fit perfectly!

  9. Quality product, bolts too short

    Posted by Unknown

    This is a quality product and I recommend it to anyone who is needing to mate an aftermarket 3in DP to an OEM or OEM-like 2.5in catback exhaust (a Borla CBE for example). Fit well, thick metal, high quality. This would have been 5 stars but the included bolts were not long enough! Wouldn't fit. A quick run to the hardware store was all it took, but c'mon guys, you took all that time and effort to make a top quality product, only to skimp on the bolts?!
    Tip to buyers: don't forget to add the donut gasket to your order!

    Matt@GrimmSpeed: Give us a call and we'd be happy to send you the correct hardware! We've never had this issue, so I suspect that either you've got an exhaust fitment issue or the wrong bolts were packaged accidentally. Either way, our customer service guys would be happy to help.

  10. Bolts too short

    Posted by Andrew Sharicz

    "The part itself is good. Be wary the bolts that come with it are too short for many DPs out there, in my case with a Perrin pipe I could not get it threaded on with a washer, I had to go without for now.

    Shame on you Grimmspeed, when the product is a universal part, you should make sure the bolts are plenty long, not like there is a clearance issue at the DP flange.

    Review marked down because it is really annoying to have to complete a product when the included hardware is inadequate."

Showing reviews 1-10 of 12 | Next