Description
The CTS Turbo BOSS800 Hybrid Turbocharger Upgrade is engineered for the Audi and Porsche EA839 3.0T platform, delivering substantial airflow gains while maintaining OEM-style fitment, drivability, and responsiveness. This turbocharger is a direct replacement upgrade designed to improve boost efficiency and top-end power without sacrificing low-RPM performance.
The BOSS800 utilizes an upgraded compressor and turbine configuration, allowing it to support a wide range of fuel blends from pump gas to ethanol mixes. Testing was performed on the same vehicle and hardware, with only fuel content changed between runs, ensuring consistent and reliable performance data.
Power output scales predictably with increased ethanol content, producing strong midrange torque and sustained power through the upper RPM range. Boost delivery remains smooth and controlled, making this turbo ideal for both street-driven and track-focused builds. The turbo pulls hard all the way to redline and offers additional headroom with upgraded fueling.
This is a brand-new complete turbocharger that does not require a core return and is compatible with many off-the-shelf Stage 3 tuning solutions.
Turbocharger Specifications
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66mm turbo inlet (larger turbo inlet required)
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66mm 7+7 design billet compressor wheel
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63mm 9-blade high-flow turbine wheel
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Stainless steel exhaust housing matched to increased turbine flow
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Heavy-duty bearings and thrust washers
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VSR balanced
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Compatible with any exhaust system
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Compatible with any charge pipe
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Compatible with 66mm turbo inlet systems
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Transfer of factory diverter valve required
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Transfer of boost pressure relief valve required (06M133554A, installation orientation is critical)
Dyno Results
All results achieved on the same vehicle with only fuel content changed.
Run 1 – 92 Octane
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561 HP
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~532 lb-ft torque
Run 2 – E50 (92 + pump ethanol)
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640 HP
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~643 lb-ft torque
Run 3 – E55 (92 + pump ethanol)
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658 HP
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~654 lb-ft torque
Run 4 – E60 (92 + pump ethanol)
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671 HP
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~663 lb-ft torque
Note: These results were achieved with full bolt-on modifications, upgraded fueling components, RS6 injectors, HPFP and LPFP upgrades, 4-BAR MAP sensors, and Logic Street Performance Stage 3 tuning. Actual results may vary depending on setup and tuning.
Parts Required for Installation (Not Included)
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2x 06M253039G – Exhaust manifold gasket
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1x 059253232C – Exhaust ring gasket
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1x WHT006901A – Oil feed O-ring
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3x WHT007689 – Oil feed and coolant O-rings
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4x WHT004982 – Barrel nut
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4x N91130801 – Exhaust nut
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1x WHT007923 – Connecting pipe O-ring
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2x 8K0253115K – Exhaust gasket
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1x N0138441 – Seal for boost pressure relief (jet) valve
Vehicle Fitment (EA839 3.0T Engines)
Check with your tuner for software compatibility.
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2018–2023 Audi B9 / B9.5 S4 3.0T
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2018–2023 Audi B9 / B9.5 S5 3.0T
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2018–2023 Audi B9 / B9.5 SQ5 3.0T
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2020–2022 Audi Q7 3.0T (4M)
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2019–2022 Audi Q8 3.0T (4M)
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2019–2022 Audi A6 3.0T (C8)
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2019–2022 Audi A7 3.0T (C8)
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2020–2024 Audi Allroad 3.0T (C8)
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2019–2023 Audi A8 3.0T (D5)
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2019–2021 Porsche Macan S 3.0T
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2019–2023 Porsche Cayenne 3.0T
Generation Summary
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Audi S4: 2018–2024
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Audi S5: 2018–2024
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Audi SQ5: 2018–2024
The CTS Turbo BOSS800 Hybrid Turbocharger delivers OEM-level fitment with serious Stage 3 power potential, making it the ideal upgrade for EA839 3.0T owners seeking reliable, scalable performance from daily driving to full ethanol builds.
