As you may already know, Aprilia has finally moved away from its decade-long design using a single catalytic converter inside the tailpipe. For the new 2025 RSV4 and TuonoV4 (Euro 5+ compliant), the OEM exhaust system now features a dual catalytic converter integrated into the header “kat-box”, located right under the engine.
This change means that for any racing conversion, replacing only the slip-on is no longer sufficient — the catalytic section is now part of the headers.
Several brands now offer full exhaust systems for these bikes — Akrapovic, SC-Project, and Spark, among others. Spark remains a top choice for those who want full titanium racing headers kit, compatible with any slip-on designed for the 2021+ layout with reversed swingarm (including the OEM silencer). Akrapovic and SC, instead, only offer full systems where the specific slip-on must be used.
The Smart Alternative: Arrow De-Kat Midpipe
A new and highly interesting solution has now arrived — the Arrow Racing De-Kat Midpipe.
This stainless-steel link pipe replaces the catalytic “kat-box” in the OEM headers, retaining the stock primary tubes and flanges.
It’s a cost-effective alternative to full titanium systems, also easily installed as only the front section of the stock headers needs to be removed.
Performance-wise, the Arrow midpipe performs exceptionally well on the TuonoV4, with results close to those of a full system. On the RSV4, full systems still have a slight advantage in the upper revs but the performance-to-cost ratio of the Arrow midpipe is extremely compelling.
It fits perfectly with:
- The stock silencer
- SC Project homologated slip-ons
- And any racing slip-on made for OEM headers (2021+ models)
Mapping Compatibility
Dedicated UpMap race maps are available, maned “RACE ARW”
- FR maps – if using a full racing slip-on
- OEM-N maps – for stock or SC homologated slip-ons (retaining the “closed in neutral / open in gear” logic for the exhaust valve)
For best results, pair the Arrow midpipe with:
- Our STACKS kit on RSV4
- Our AIRBOX + STACKS kits on TuonoV4 and the corresponding UpMap calibrations.
Installation Manual Download
Some Arrow kits have been shipped without the printed installation manual inside the box.
You can download the official fitting instructions (PDF) here:
Download the Arrow Midpipe Installation Manual
The manual covers step-by-step installation, torque specifications, and important safety notes in Italian, English, and French.
Watch the Video
Check out this short video showing the the Arrow De-Kat Midpipe on the dyno, it was a prototype made in Titanium, used to build the specific UpMap maps:
Buy Online
The Arrow Racing De-Kat Midpipe for Aprilia RSV4 / TuonoV4 2025–2026 (Euro 5+) is available now at: aspecialparts.com – product page
Final Notes
Arrow’s craftsmanship and fitment precision are excellent, as expected. Installation is straightforward and usually takes just a couple of hours. Upmap ECU-reflash just needs about 15 minutes.
This midpipe is an ideal solution for those who want a racing setup with minimal cost, reduced weight, and significant performance gains – without committing to a full titanium exhaust system.
