CTS Turbo BOSS800 Hybrid Turbocharger Upgrade for B9 Audi S4, Audi S5, Audi SQ5

We are excited to announce our new BOSS800 hybrid turbo for the Audi/Porsche EA839 3.0T platform. This is a direct replacement upgrade that significantly increases airflow while retaining OEM-style fitment and drivability. This hybrid unit is optimized for higher boost efficiency and improved top-end power without sacrificing low-RPM response. The turbo utilizes an upgraded compressor and turbine configuration, allowing it to support a wide range of fuel blends from pump gas to ethanol mixes. All testing shown was performed on the same vehicle and hardware, with only fuel content changed between runs.

Power gains scale predictably with ethanol content, showing strong midrange torque and sustained power through the upper RPM range. Boost response remains smooth and controlled, making the turbo suitable for both street and track-focused builds. This turbo pulls all the way to redline and has more potential with additional fueling.

The best part is that this is a full brand-new unit that does not require a core and it is compatible with many off-the-shelf stage 3 tuning.

Turbocharger specs:

• 66mm turbo inlet, larger turbo inlet is required
• 66mm 7+7 design billet compressor wheel
• 63mm 9 blade high-flow turbine wheel
• Stainless steel exhaust housing, matched to increased flow of the turbine wheel
• Heavy duty bearings and thrust washers
• VSR balanced
• Compatible with any exhaust, any charge pipe, and 66mm turbo inlet
• Transfer of factory diverter valve and boost pressure relief valve (06M133554A, pay attention on how it is installed).

Dyno Results from our friends at Logic Street Performance (1/4 mile time: 10.29 at 140mph)

• Run 1 – 92 Octane:
  561 hp / ~532 lb-ft

• Run 2 – E50 (92 + pump E):
  640 hp / ~643 lb-ft

• Run 3 – E55 (92 + pump E):
  658 hp / ~654 lb-ft

• Run 4 – E60 (92 + pump E):
  671 hp / ~663 lb-ft

**Note that these results were achieved in a vehicle with full bolt-ons and upgraded fueling system (RS6 injectors, HPFP and LPFP upgrade, 4BAR Map sensors) and Logic Street Performance stage 3 tuning. Your result may vary.

Parts required for installation (not included):

• 2x 06M253039G – exhaust manifold gasket
• 1x 059253232C – exhaust ring gasket
• 1x WHT006901A – oil feed o-ring
• 3x WHT007689 – oil feed and coolant o-ring
• 4x WHT004982 – barrel nut
• 4x N91130801 – exhaust nut
• 1x WHT007923 – connecting pipe o-ring
• 2x 8K0253115K – exhaust gasket
• 1x N0138441 – seal for boost pressure relief (jet) valve

• 2018 – 2023 B9/B9.5 Audi S4 3.0T
• 2018 – 2023 B9/B9.5 Audi S5 3.0T
• 2018 – 2023 B9/B9.5 Audi SQ5 3.0T
• 2020 – 2022 4M Audi Q7 3.0T
• 2019 – 2022 4M Audi Q8 3.0T
• 2019 – 2022 C8 Audi A6 3.0T
• 2019 – 2022 C8 Audi A7 3.0T
• 2020 – 2024 C8 Audi AllRoad 3.0T
• 2019 – 2023 D5 Audi A8 3.0T
• 2020 – 2021 Porsche Macan S 3.0T *must have EA839 engine
• 2020 – 2023 Porsche Cayenne 3.0T *must have EA839 engine