Invidia N1 Cat-Back Exhaust | 2015-2021 Subaru WRX / WRX STi | 4-Door Sedan | Titanium Tips | HS15STIGTT
Invidia N1 Cat-Back Exhaust – 2015–2021 Subaru WRX / WRX STi | 4-Door Sedan | Titanium Tips | HS15STIGTT
⚠️ SOUND LEVEL NOTE — The N1 is Invidia’s aggressive exhaust line. It is loud — particularly during acceleration and at wide-open throttle. Highway drone at cruising speeds is a known characteristic of this system. If you want a more refined sound with less drone, consider the Invidia Q300 instead. The N1 is the right choice if you want maximum aggression.
⚠️ 4-DOOR SEDAN ONLY — Fits the 2015–2021 Subaru WRX and WRX STi 4-door sedan (VA chassis). Does not fit hatchback or wagon bodystyles.
Invidia’s N1 cat-back exhaust for the 2015–2021 Subaru WRX (FA20DIT) and WRX STi (EJ257) 4-door sedan. Mandrel-bent SUS304 stainless steel throughout, twin outlet with single-layer titanium burnt-finish tips. One of the most widely-used cat-back exhausts in the WRX/STi community — known for its aggressive boxer-engine exhaust note and straightforward bolt-on installation. Manufacturer-claimed gains of +12 HP / +15 lb-ft torque on a stock vehicle (Invidia dyno figures). 56.4 lbs shipped.
N1 Sound Character
The N1 produces a loud, aggressive exhaust note that emphasises the WRX/STi’s flat-four boxer character. At idle it’s a deep, rumbling tone. Under acceleration it builds to an aggressive, high-pitched exhaust note at higher RPM. At highway cruising speeds (100–120 km/h), moderate-to-noticeable drone is present in the cabin — this is inherent to the N1’s design and widely documented. This is not a defect. If highway drone is a concern, the Invidia Q300 uses a resonator to reduce drone while retaining most of the N1’s tone.
Construction
- SUS304 Stainless Steel: Premium Japanese stainless throughout — corrosion-resistant, durable, handles the thermal cycling of daily and track use
- Mandrel Bent: All bends are mandrel-formed to maintain a consistent internal diameter — no crimping or flow restriction at bend points
- Single-Layer Titanium Tips: Twin outlet titanium tips with a burnt finish — lightweight, corrosion-resistant, and visually distinctive. The burnt titanium colouring develops naturally from exhaust heat
- Bolt-On Installation: Direct replacement for the factory cat-back — connects at the mid-pipe. No cutting or welding required. Includes gaskets and hardware
Power Gains
Invidia’s dyno testing shows +12 HP / +15 lb-ft torque on a stock WRX or STi from the N1 cat-back alone. These are manufacturer figures on a baseline stock vehicle — real-world results will vary by tune, condition, and supporting modifications. When paired with a downpipe and ECU tune (e.g. Cobb Accessport Stage 2), the cat-back supports higher overall power levels as part of a full exhaust system upgrade.
Fitment
- 2015–2021 Subaru WRX VA — FA20DIT — 4-door sedan
- 2015–2021 Subaru WRX STi VA — EJ257 — 4-door sedan
- 4-door sedan only — does not fit hatchback or wagon
4-door sedan only. Loud exhaust — verify local noise regulations before purchasing. Highway drone is a known characteristic of the N1. Professional installation recommended. Pre-soak factory hardware with penetrating oil before removal. Apply anti-seize to all bolts during installation. Check for exhaust leaks after installation and re-torque after first heat cycle. +12 HP / +15 lb-ft are Invidia manufacturer dyno figures on a stock vehicle — results vary.
Specifications
- Brand: Invidia
- Part Number: HS15STIGTT
- Series: N1
- Type: Cat-back exhaust
- Outlet: Twin
- Tips: Single-layer titanium — burnt finish
- Material: SUS304 stainless steel
- Construction: Mandrel bent
- Weight: 56.4 lbs
- Claimed Power Gain: +12 HP / +15 lb-ft (Invidia dyno, stock vehicle)
- Application: 2015–2021 Subaru WRX / WRX STi VA — 4-door sedan
- Includes: Complete cat-back system, titanium tips, gaskets, hardware, instructions