Akrapovic 991 Turbo Exhaust: 991.1 Slip-On (14-15)

The Akrapovic 991 Turbo exhaust is the upgrade discerning owners reach for when the factory system no longer matches the car. For the first-generation 991.1 Porsche 911 Turbo and Turbo S — the 2014 and 2015 model years built around the 3.8-liter twin-turbocharged flat-six — Akrapovic offers a single, focused flagship: the Slip-On Line (Titanium) with handcrafted carbon-fiber and titanium tailpipes. It is engineered specifically for the 991.1 chassis, mounting in place of the OE rear silencer to cut weight, free up flow, and give the Turbo a sound worthy of its 513 to 552 horsepower.

What Akrapovic offers for the 991.1 Turbo

Akrapovic builds its 911 Turbo program around the Slip-On Line, and for the 991.1 generation that means one comprehensive titanium system designed to replace the heavy factory rear muffler. Unlike a full turbo-back kit, a Slip-On retains the car's original catalytic converters and primary plumbing, which keeps installation straightforward, preserves emissions compliance, and avoids check-engine complications — while delivering the bulk of the weight savings and the sound transformation owners actually want.

The headline system carried by NLP Performance is the Slip-On Line (Titanium) with carbon-fiber and titanium tips, part number S-PO991TSO-HT. It is the same architecture Akrapovic fits across the 991.1 Turbo lineup, with a tailpipe set finished to show-quality standards. For owners who later want even more, Akrapovic's catalog also includes optional Link Pipe sets (with or without sport catalysts) and a rear carbon-fiber diffuser that bolt onto this same core system to push performance and visual aggression further.

The flagship: Slip-On Line (Titanium) construction

Everything that matters in this system starts with the material. The Slip-On Line is fabricated from a high-grade titanium alloy — the same family of metals Akrapovic refined through decades of MotoGP and Formula competition. Titanium's strength-to-weight ratio lets Akrapovic build muffler walls thinner and lighter than steel while withstanding the heat of a hard-driven twin-turbo flat-six. The result is a rear silencer that weighs a fraction of the cast, double-walled factory unit.

The tailpipes are where craft meets function. Each tip is hand-finished from carbon fiber paired with titanium, giving the rear valance a purposeful, race-derived look that distinguishes a 991 Turbo at a glance. Internal flow paths are optimized over the restrictive OE silencer, so the engine breathes more freely on the exhaust side without sacrificing the daily-driving manners that make a 911 Turbo so usable.

Tailpipes & tips: carbon fiber and titanium

The tailpipe set is integral to this system rather than a separate purchase — the carbon/titanium tips ship as part of the S-PO991TSO-HT kit. Akrapovic finishes the titanium with its signature heat-treated coloring, and the carbon-fiber outer sleeves are laid up and lacquered by hand. Beyond the visual upgrade, the tip geometry is tuned to project the new exhaust note cleanly out of the rear diffuser area, so the sound the system produces actually reaches the cabin and bystanders the way Akrapovic's engineers intended.

Weight savings & materials

Weight is the Slip-On Line's most measurable benefit. Akrapovic's published figures put the titanium system at roughly 43.7 pounds against approximately 63.1 pounds for the factory exhaust — a reduction of about 14 pounds, or close to 6.4 kg. On a rear-engined 911 that mass comes off the very back of the car, where it has an outsized effect on polar moment and rotational inertia. Less weight hanging behind the rear axle line means the Turbo changes direction with slightly less reluctance and rides with a touch less heft over its tail.

That weight story is entirely a function of materials. Titanium is far lighter than the stainless steel used in OE silencers, and the carbon-fiber tip sleeves shave additional grams at the extreme rear of the car. For a chassis as finely balanced as the 991.1 Turbo, this is meaningful unsprung-adjacent and rear-biased weight that no software tune can replicate.

Sound & performance: what to expect

The 991.1 Turbo's flat-six is a forced-induction engine, so its acoustic character differs from a naturally aspirated GT3 — turbochargers naturally muffle some upper-register edge. The Slip-On Line works with that, deepening the tone and adding a richer, sportier voice at lower revs that builds into a more dynamic, harder-edged note under throttle. It is a step up in presence and authority rather than an obnoxious drone, which is exactly the brief for a grand-touring supercar that still has to behave on a long highway run.

On the dyno, Akrapovic publishes modest gains for this slip-on configuration — on the order of roughly 7 to 8 horsepower and around 10 to 11 lb-ft of torque at the points where the engine breathes against the rear silencer. The bigger performance argument, though, is the weight reduction and the freer-flowing rear section, which together sharpen throttle response and help the engine spin up. Owners who later add the optional Link Pipe set (with or without sport catalysts) and an ECU remap can extract considerably more, but even unmodified the Slip-On delivers a noticeably more eager, more vocal Turbo.

Sound control & valve behavior

The 991.1 Turbo and Turbo S left the factory with a switchable sport exhaust, and the Akrapovic Slip-On Line is engineered to work with the car's existing valve-control system on cars fitted with the OE sport exhaust. That means you keep the familiar quiet-versus-loud behavior — civilized when you want it, vocal when you press the button — only now with titanium hardware and a more characterful tone behind it. For owners who want manual control or who are working from a non-sport OE setup, Akrapovic's Sound Kit and Link Pipe accessories address those configurations, though some combinations change the system's homologation status.

Fitment: exact years, engine, and variants

This system is built for the first-generation 991.1 Porsche 911 Turbo platform: model years 2014 and 2015, covering both the 911 Turbo (3.8L twin-turbo flat-six, 520 PS / 513 hp) and the 911 Turbo S (560 PS / 552 hp). Both Coupe and Cabriolet bodystyles share the same rear exhaust architecture, so the Slip-On Line applies across the 991.1 Turbo range. It is specific to the 991.1 — later 991.2 Turbo cars (2017 onward) use a different system, so confirm your build year before ordering.

At NLP Performance we list this system precisely against the 991.1 chassis to keep fitment unambiguous, and our team is always happy to confirm your VIN against the correct part before you buy.

Installation & what's required

Because it is a slip-on, the S-PO991TSO-HT replaces the rear silencer section and reuses the factory mounting points, hangers, and catalytic converters — one of the reasons a Slip-On Line is far less invasive than a full turbo-back build. The carbon/titanium tips are included in the kit, so there is no separate tip purchase to track down. Installation is straightforward for a competent Porsche specialist, and because the system is designed around the OE valve control, no tune is required for cars running the standard sport exhaust setup.

The optional upgrade path is clear: add the Akrapovic Link Pipe set (with or without sport cats) and an ECU remap to chase more power, or fit the rear carbon-fiber diffuser for a more aggressive look. None of those are required to enjoy the Slip-On Line on its own.