Subaru WRX STI VA 4" Catback: Sound and Fit Guide

By REMARK Exhaust | Published: 2026-10-26

Category: How-to Guides

Learn how the 4" catback changes the WRX STI VA's sound, what to check before installation, and step-by-step fitting tips to avoid common mistakes.

Quick answer

For a WRX STI VA, a 4-inch catback like the REMARK Sports Touring Exhaust gives a deeper, richer tone with aggressive tips, but you must remove the factory donut gasket and avoid aftermarket adapters for a correct fit.

Why the 4-inch catback changes the sound

The 4-inch tips and redesigned dual mufflers on the REMARK Sports Touring Exhaust are engineered to amplify a rich, powerful note. Compared to a stock system, you get more presence without the raspy drone that some aftermarket systems produce.

You can choose between non-resonated and resonated stainless steel versions. The resonated option uses a resonator to tone down the volume and reduce drone, while the non-resonated version is louder and more aggressive. Pick based on how much noise you want on daily drives.

Fitment considerations for the VA chassis

This catback is designed specifically for the 2015-2021 WRX/STI VA. The fitment is direct, but you must remove the factory donut gasket that sits between the mid-pipe and the catback. Leaving it in place can cause leaks or misalignment.

REMARK explicitly advises against using aftermarket adapters. Adapters can shift the pipe angles and cause incorrect fitment, leading to rattles or stress on the hangers. Stick with the supplied hardware and follow the torque specs.

Installation steps for the 4" catback

Prep the car and tools: Park on a level surface, chock the rear wheels, and raise the rear with jack stands. Gather a 12mm socket, 14mm socket, penetrating oil, and a torque wrench. Check that the exhaust is cool before starting to avoid burns.
Remove the factory catback: Spray the exhaust hangers and bolts with penetrating oil. Remove the bolts at the mid-pipe connection and the hangers from the rubber isolators. Lower the factory catback carefully—it is heavy. Keep the factory donut gasket aside; you will not reuse it.
Install the new catback: Position the REMARK system on the hangers, but leave the clamps loose. Connect the mid-pipe to the catback without the donut gasket. Align the tips evenly in the bumper cutout before tightening. Do not use aftermarket adapters; they can cause misalignment.
Tighten and check for leaks: Tighten all clamps and bolts to spec, starting from the front and working back. Start the engine and check for exhaust leaks at every joint while the car is on stands. Re-check the clamps after a short test drive as they can settle.

Product spotlight

Sports Touring Exhaust (4" Catback) - Subaru WRX/STI VA [2015~2021]: Redesigned dual mufflers with aggressive 4-inch tips that amplify a rich powerful note. This gives you a deeper, more present exhaust tone without the need for a full turbo-back system.
Sports Touring Exhaust (4" Catback) - Subaru WRX/STI VA [2015~2021]

Once installed, take a short drive and listen for any rattles or leaks. If the sound is too loud, consider the resonated version or add a resonator in the future.