Subaru WRX STI Exhaust Layout

Subaru Impreza Turbo Exhaust System Layout with Diagrams

In this article we cover the exhaust layout and system for Subaru Impreza Classic 1993-2000, New Age Blobeye 2001-2005, Hawkeye 2006-2007 and Hatchback / Saloon 2008-2013, and STI 2014-2019, along with gasket locations and diagrams.

Impreza GC8 1993-2000 Classic Models UK Turbo WRX and STI

L-Impreza-Catalunya-big-600x390-1 Subaru Impreza Turbo Exhaust System Layout with Diagrams

The Impreza GC8 Classic Turbo uses a 3 piece exhaust from the turbo back. This comprises a long downpipe, originally fitted with a catalytic converter, a center section with catalytic converter or straight through for some JDM import models and a rear silencer. Bore size is approximately 2.5″ internal diameter and the exhaust was made from mild steel.

From the Engine the layout is as follows

  1. Exhaust Manifold
  2. Exhaust Uppipe to Turbo. A straight through pipe with no catalytic converters or silencers
  3. Exhaust Downpipe from Turbo to Centre Section. Originally contained a large catalytic converter element to pass emission regulations
  4. Exhaust Centre Section from Downpipe to Rear Silencer. Normally contained both a smaller catalytic converter and resonator / silencer (UK / Euro models) or just the silencer (mostly JDM imports). This is normally around 137cm flange to flange.
  5. Exhaust Rear Silencer, with 3 integrated hangers to hang on the exhaust rubber mounts.

The exhaust sections are joined together with a series of gaskets and bolts of varying sizes and designs. See our site at this link for details of these https://scoobyparts.com/subaru-impreza-wrx-sti-exhausts/subaru-exhaust-gaskets-and-bolts

exhaust-layout-classic-impreza Subaru Impreza Turbo Exhaust System Layout with Diagrams
Impreza Classic Turbo Exhaust Layout

Impreza 2001-2005 2.0 WRX and STI – UK models.

WRX-300-600x390-1 Subaru Impreza Turbo Exhaust System Layout with Diagrams

The later Bugeye and Blobeye 2.0 Litre WRX and STI models used a variation on the classic system, with a similar exhaust manifold and Uppipe. On WRX models the Uppipe was fitted with small catalytic converter, not present on the STI. Followed after Turbo by a shorter Downpipe, the addition of a Catpipe, a shorter 127cm length Centre Section and a redesigned rear silencer.

From the engine the exhaust layout is therefore as follows

  1. Exhaust Manifold
  2. Exhaust Uppipe to Turbo. A straight through pipe with no catalytic converters or silencers on STI models and a catalytic converter on the WRX models.
  3. Exhaust Downpipe from Turbo to Cat Pipe. Originally contained a large catalytic converter element to pass emission regulations.
  4. Exhaust Catpipe – fitted between Downpipe and Centre section houses a smaller catalytic converter.
  5. Exhaust Centre Section to Rear Silencer. Normally contained a resonator / silencer. This is normally around 127cm in length flange to flange.
  6. Exhaust Rear Silencer, with 3 integrated hangers to hang on the exhaust rubber mounts. This was a slightly different design to the Classic rear silencer
exhaust-layout-newage-impreza-1 Subaru Impreza Turbo Exhaust System Layout with Diagrams
Impreza New Age 2001-2005 Exhaust Layout

Subaru Impreza 2006-2007 2.5 WRX and STI – UK models.

RB320-600x389-3 Subaru Impreza Turbo Exhaust System Layout with Diagrams

The 2006-2007 2.5 Litre Hawkeye WRX and STI models used a variation on the New Age 2001-2005 system, with same exhaust manifold and Uppipe but with a shorted downpipe and longer Catpipe.  There was no catalytic converter fitted to the Uppipes on these 2.5 Litre models.  Followed after Turbo by a short Downpipe, longer Catpipe, the identical 127cm length Centre Section and similar sized rear silencer.

From the engine the exhaust layout is therefore as follows

  1. Exhaust Manifold
  2. Exhaust Uppipe to Turbo. A straight through pipe with no catalytic converters or silencers.
  3. Exhaust Downpipe from Turbo to Cat Pipe. Originally contained a large catalytic converter element to pass emission regulations.
  4. Exhaust Catpipe – fitted between Downpipe and Centre section houses a smaller catalytic converter.
  5. Exhaust Centre Section to Rear Silencer. Normally contained a resonator / silencer. This is normally around 127cm in length flange to flange.
  6. Exhaust Rear Silencer, with 3 integrated hangers to hang on the exhaust rubber mounts. This was a slightly different design to the Classic rear silencer.
exhaust-layout-newage-impreza Subaru Impreza Turbo Exhaust System Layout with Diagrams
Exhaust Layout – Impreza 2006-2007 UK WRX and STI

Subaru Impreza Hatchback 2008-2012 WRX and STI

330-S-hatch-black-one..-and-silver-sti-600x390-2 Subaru Impreza Turbo Exhaust System Layout with Diagrams

The Hatchback models from 2008 to 2012 used a similar setup to the Hawkeye exhaust system, with again the same exhaust Manifold, Uppipe and similar downpipe but with a longer Catpipe, longer Centre Section and then either a single exit tailpipe for the WRX models or a twin configuration for the STI models.

  1. Exhaust Manifold
  2. Exhaust Uppipe to Turbo. A straight through pipe with no catalytic converters or silencers.
  3. Exhaust Downpipe from Turbo to Cat Pipe. Originally contained a large catalytic converter element to pass emission regulations.
  4. Exhaust Catpipe, longer than the Hawkeye model- fitted between Downpipe and Centre section houses a smaller catalytic converter.
  5. Exhaust Centre Section to Rear Silencer. Normally contained a resonator / silencer and of a completely different length and design to the previous Hawkeye models.
  6. Exhaust Rear Silencer, with either single (WRX) or quad exit tailpipes (STI)

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