The factory downpipe on the 2015 and newer Subaru WRX is one of the more restrictive points in the exhaust system. Because it sits directly after the turbo, restriction here has an outsized effect on how efficiently the turbo can do its job. The Invidia Stainless Downpipe with Divorced Wastegate and High Flow Cat replaces that factory unit with a freer-flowing design built specifically for the WRX with an automatic transmission.
This post covers what the downpipe does, what the divorced wastegate design means, and what changes once it is installed.
What This Downpipe Does
The Invidia downpipe is constructed from stainless steel with a one-piece design that eliminates the factory catalytic converter setup and replaces it with a single high flow cat. A large 4 inch stainless steel bellmouth sits at the turbo outlet, which frees up exhaust gas flow right where the factory unit is most restrictive. The 3 inch piping carries that improved flow downstream to the rest of the exhaust system.
Because the downpipe sits immediately after the turbo, reducing backpressure at this point allows the turbo to spool more efficiently and exhale exhaust gases with less resistance. The result is improved turbo response and a measurable increase in power and torque over the factory setup, even before any other modifications are made.
What Divorced Wastegate Means
The 2015 and newer WRX uses a divorced wastegate turbo design, where the wastegate housing is separate from the main turbine housing rather than integrated into a single casting. This downpipe is built specifically around that architecture. A divorced wastegate downpipe includes a separate path for the wastegate flow that rejoins the main exhaust stream downstream, which is different from how older integrated wastegate designs route exhaust.
Because this design matches the factory turbo architecture on the 2015 and newer WRX, the downpipe bolts on without requiring modifications to the turbo or wastegate plumbing. This is part of why a divorced wastegate downpipe is the correct category of part for this platform, rather than a downpipe designed for an integrated wastegate turbo from an earlier generation.
Fitment
This specific downpipe fits the 2015 to 2021 Subaru WRX with an automatic transmission, across Base, Premium, and Limited trims. It does not fit manual transmission WRX models, and it does not fit the STI, since the STI platform does not use this transmission or turbo configuration. WRX owners with a manual transmission should confirm fitment on the manual-specific version of this downpipe before ordering.
High Flow Cat and Emissions
This downpipe includes a high flow catalytic converter rather than running catless. The high flow cat provides meaningfully better flow than the factory catalytic converter while still maintaining some emissions control, unlike a fully catless downpipe. However, the high flow cat downpipe is not emissions legal in all jurisdictions and may still trigger a check engine light in some cases, since the reduced cat density can affect how the factory oxygen sensors read exhaust gas composition.
For WRX owners in regions with strict emissions testing, confirming local regulations before installing a high flow cat downpipe is worth doing ahead of time. The high flow cat also helps moderate boost spike by maintaining some backpressure in the system, which keeps the turbo operating in a more predictable range compared to a fully catless setup.
What Changes After Installation
The most immediate change after installing this downpipe is in turbo response. Reduced backpressure at the turbo outlet allows the turbo to spool faster and recover boost more quickly between gear changes. Sound also changes noticeably, since the reduced cat density and improved flow path produce a deeper, more aggressive exhaust tone, particularly under load.
On a stock or lightly modified WRX, the power gains from a downpipe alone are real but modest. The larger gains come when the downpipe is paired with a supporting tune, since the factory ECU calibration is built around the more restrictive factory downpipe. Without a tune, the ECU may not fully take advantage of the improved exhaust flow, and in some cases the change in backpressure can affect how the factory tune manages boost. For WRX owners planning a downpipe upgrade, pairing it with a tune from the start is the more effective approach. The EFI tuning post covers what tuning does and why it matters alongside exhaust upgrades like this one.
Where This Fits in a WRX Build
A downpipe upgrade is one of the more impactful early modifications on the WRX platform because of its direct effect on turbo efficiency. For owners planning a broader exhaust upgrade, the downpipe vs catback vs turboback post explains how this upgrade compares to other exhaust modifications and where it fits in the priority order.
For WRX owners working through a broader build plan, the WRX exhaust upgrades hub covers the full range of exhaust options and how they work together. The WRX performance upgrades hub covers how exhaust upgrades fit into the broader build sequence alongside turbo, fueling, and tuning.
Shop the Invidia Stainless Downpipe
The Invidia Stainless Downpipe with Divorced Wastegate and High Flow Cat for WRX CVT is in stock and ships in 24 to 48 hours. Priced at $1,247.54.
Shop the Invidia Stainless Downpipe for WRX CVT 2015 to 2021
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