What You Get with the APR Stage 3 Kit

The APR Stage 3 Kit is a comprehensive forced-induction upgrade engineered specifically for the Audi RS5’s 4.2L V8 (for the 2013‑2015 B8.5 chassis) and later the 2.9L twin-turbo V6 (B9/B9.5). The kit moves far beyond a simple software flash; it replaces core air and fuel hardware so the engine can safely produce over 100 hp more than stock. Every component is matched to APR’s proprietary calibration, which means you don’t have to worry about piecing together parts from different brands.

  • GT-Series Hybrid Turbocharger – Larger compressor wheel and revised housing for higher boost without sacrificing spool response.
  • Upgraded Intercooler – Bar-and-plate core with 40% more volume to keep intake air temperatures in check during aggressive driving.
  • High-Flow Fuel Injectors – Sized to deliver the additional fuel required at higher boost levels; all RS5 injectors are direct-injection units matched to APR’s flow specs.
  • 9‑Layer Silicone Intake Hose & High-Flow Air Filter – Reduces restriction upstream of the turbo, improving volumetric efficiency.
  • APR Stage 3 ECU & TCU Tune – Custom calibration that optimizes ignition timing, fuel pressure, boost targets, and transmission shift points.

The kit is designed as a direct bolt-on; no permanent modifications to the engine bay are required, and all factory mounting points are reused. APR recommends the kit for dedicated enthusiasts who want track-worthy power without losing daily drivability.

Breaking Down the Total Cost

Pricing for the APR Stage 3 Kit varies by vehicle generation and any optional supporting modifications. Here is a realistic budget breakdown based on current market data and typical shop rates.

  • APR Stage 3 Kit (parts only): $7,500 – $10,200 depending on RS5 generation and whether you include the optional APR Downpipe.
  • Installation Labor: $1,200 – $2,200. Book time for the B8.5 is about 12–14 hours; B9/B9.5 takes slightly longer due to tighter engine bay packaging.
  • Additional Supporting Modifications: $400 – $1,800. Items such as colder spark plugs (NGK 2-step), APR carbon-fiber intake pipe, or a high-flow catalyst can add cost but improve consistency.
  • Optional TCU Tune: Usually $500–$800 if not bundled with the kit. A transmission tune is essential for DSG cars to handle the increased torque and to enable launch control at higher RPM.

Total out-of-pocket can land between $9,600 and $14,000. While the initial price may seem steep, it is still about half the cost of a custom twin-turbo conversion and includes a warranty from APR if installed by an authorized dealer.

Installation Process – What to Expect

Installing the APR Stage 3 Kit is an involved job best left to a shop with experience in German forced-induction conversions. A qualified technician can complete the work in a single full day (8–12 hours), but first-time installers should plan for a weekend. Below is a step-by-step overview.

Preparation and Safety

  • Disconnect the battery negative terminal (12‑hour reset to clear adaptions).
  • Drain engine coolant and remove the front bumper assembly for intercooler access.
  • Remove the belly pan, intake ducting, and air box.
  • On the B8.5, the supercharger (if present on earlier 3.0T) or the entire intake manifold for the 4.2L V8 must come off to reach the fuel injectors.

Removing the Factory Turbo and Intercooler

  • Unbolt the factory turbocharger from the exhaust manifold(s). On the B9 RS5, both turbos are replaced with a single larger unit from the kit.
  • Disconnect coolant and oil lines from the turbo.
  • Remove the stock intercooler (usually a side-mount or thin bar‑and‑plate unit).
  • Extract the factory fuel injectors using a proper puller tool to avoid damaging the high-pressure fuel rail.

Installing the APR Components

  • Mount the new intercooler in the stock location, securing it with the included brackets.
  • Bolt the GT-series turbocharger onto the manifold(s) using a new gasket set. Torque all fasteners to APR’s specifications.
  • Connect the upgraded fuel injectors and rail; ensure O‑rings are lubricated with clean motor oil.
  • Route the silicone intake hose from the turbo inlet to the APR high-flow air filter.
  • Reattach all coolant and oil lines, then refill with the correct Audi-spec fluids.

ECU and TCU Calibration

Once the hardware is physically installed, the critical step is flashing the APR Stage 3 software. The technician connects a laptop or APR’s handheld programmer to the OBD‑II port. The process writes new fuel, ignition, and boost maps into the ECU. For DSG-equipped cars, the TCU must also be reflashed to firm up shift pressure, raise the torque converter lockup threshold, and enable launch control at 3,000‑4,000 RPM.

A final road test is performed to verify lambda values, boost pressure (typically 19–22 psi on the APR gauge), and lack of codes. Minor adjustments may be made via APR’s mobile app if the shop is a certified dealer.

Real-World Performance Gains

APR publishes conservative numbers that independent dyno tests confirm. On a B9 RS5 with the 2.9T V6, the Stage 3 kit produces approximately 530–560 whp and 500–530 wtq on 93 octane pump gas. That represents a gain of over 150 wheel horsepower compared to a stock B9 RS5 (around 380 whp).

  • 0–60 mph: Drops from 3.9 seconds (stock) to roughly 3.3 seconds with proper traction.
  • Quarter‑Mile: Expect mid‑11‑second passes at 120–124 mph, depending on temperature and surface.
  • Throttle Response: The hybrid turbo spools noticeably faster than a full‑frame turbo, so part‑throttle response is near stock until 3,500 RPM, then pulls hard to redline.

For reference, a B8.5 RS5 (4.2L V8) with the APR Stage 3 kit makes around 480–500 whp, still a dramatic improvement over the factory 370 whp. The naturally aspirated V8’s sound is preserved but now accompanied by a pronounced turbo whistle.

Reliability and Supporting Modifications

APR engineers the Stage 3 kit to be safe on pump gas and with standard maintenance intervals. However, the increased heat load requires attention to a few areas:

  • Oil Quality: Use only a full synthetic 5W‑40 that meets VW 502.00/504.00. Oil change intervals should be 5,000 miles maximum.
  • Spark Plugs: Gap the NGK competition plugs to 0.024″–0.026″ per APR’s gap spec. Replace every 15,000 miles.
  • Cooling System: On track days, consider APR’s auxiliary radiator or a larger intercooler if you live in a hot climate. The stock system can handle street use but may heat‑soak with repeated pulls.
  • Fuel System: No auxiliary fuel pump is needed on the B9 up to 560 whp. The high‑pressure fuel pump (HPFP) is sufficient, but some owners upgrade the low‑pressure pump for ethanol blends (E85 not recommended without proper flex‑fuel calibration).

Many owners report 50,000+ miles trouble‑free when maintenance is kept up. The biggest risk is detonation from poor fuel; always use top‑tier 93 octane or higher.

How Stage 3 Compares to Other Tuning Paths

If you are considering modifications, understand where the Stage 3 kit fits versus other common approaches.

Stage 2 (ECU tune + downpipe)Gains 50–80 whp, modest improvement, no turbo swap. Costs around $3,500.
Stage 4 (ETRS / full frame turbo)600+ whp possible, but requires built engine, higher cost ($20k+), and reduced reliability on stock bottom end.
Custom hybrid turbo (garage built)Can be cheaper but lacks APR’s calibration development and warranty.

The APR Stage 3 is the sweet spot for drivers who want a proven, warrantied system with the power to embarrass most sports cars while keeping the interior quiet and the emissions system largely intact (if you retain the catalytic converter).

Driving Experience – On the Road and on Track

Behind the wheel, the biggest change is the mid‑range punch. The stock RS5 is quick, but the APR Stage 3 makes it feel like a completely different animal. Poweful acceleration from 50–120 mph arrives without hesitation, and the DSG shifts become crisp under the revised TCU logic.

Sound is another area of transformation. The factory exhaust note becomes deeper and more aggressive, especially with the APR downpipe option. Turbo spool is audible inside the cabin, giving the car a motorsport character. For daily driving, the kit remains civil; the car will idle smoothly and drive like stock if you keep the revs low.

On a closed course, the car demands better brakes and tires. The stock Pirellis are overwhelmed by the additional torque; consider Michelin Pilot Sport 4S or equivalent. Brake upgrades (steel‑topped lines, high‑temperature fluid) are highly recommended for repeated stops.

Maintenance Considerations After the Upgrade

Owning an APR Stage 3 RS5 means being more attentive to routine checks.

  • Intercooler Fluid: The APR intercooler is air‑to‑air, so no special fluid is needed. Inspect the silicone hoses annually for cracking.
  • Boost Leaks: Have a smoke test performed every 10,000 miles to ensure couplers are secure.
  • Carbon Cleaning: The direct‑injection engine will still accumulate carbon on the intake valves. Expect a walnut blast every 40,000–50,000 miles; the additional fuel from the stage 3 kit may increase the rate slightly.
  • Software Updates: APR occasionally releases revisions. Check with an authorized dealer for updates that improve drivability or fix rare faults.

Is the APR Stage 3 Kit Worth It?

For the owner who wants a reliable, high‑powered RS5 without the headache of piecemeal modifications, the APR Stage 3 Kit is arguably the best turnkey solution on the market. The cost is substantial, but the combination of engineering support, factory‑like fitment, and the assurance of a warranty makes it a smarter investment than a custom build. If your goal is to enjoy a truly fast, daily‑drivable RS5 that can hold its own against new BMW M3s or Porsche 911s, this kit delivers.

Before pulling the trigger, talk to an APR dealer about your specific model year and driving habits. Many shops offer bundle pricing that includes installation and a dyno tune. Once installed, you’ll understand why the APR Stage 3 is a benchmark for Audi forced‑induction upgrades.

For more technical details, visit the official APR product page. Real‑world owner experiences can be found on Audizine forums and independent dyno results are often posted on AudiWorld.