The B&B ExhaustStealth Exhaust Audi S4 1999-2001 for your 1998-2001 Audi S4 is a great way to increase horsepower and torque gains by replacing your restricted factory car exhaust system.

The B&B Exhaust System 3.5-Inch Round Double Wall Tip Audi B7 S4 Quatro 4.2L 2006-2008 for your 2003-2008 Audi S4 is a great way to increase horsepower and torque gains by replacing your restricted factory car exhaust system.

The B&B Exhaust Stealth Catback Exhaust System with 3.5-Inch Twin Round Double Wall Tips Audi S5 3.0L 2008-2020 for your 2008-2016 Audi S4 is a great way to increase horsepower and torque gains by replacing your restricted factory car exhaust system.

The B&B Exhaust Stealth Catback Exhaust System with 3.5-Inch Twin Round Double Wall Tips Audi S4 Quattro 3.0L 2009-2016 for your 2009-2016 Audi S4 is a great way to increase horsepower and torque gains by replacing your restricted factory car exhaust system.

The B&B Exhaust Sport Catback Exhaust System with 3.5-Inch Twin Round Double Wall Tips Audi S5 3.0L 2008-2020 for your 2008-2016 Audi S4 is a great way to increase horsepower and torque gains by replacing your restricted factory car exhaust system.

The B&B Exhaust Sport Catback Exhaust System with 3.5-Inch Twin Round Double Wall Tips Audi S4 Quattro 3.0L 2009-2016 for your 2009-2016 Audi S4 is a great way to increase horsepower and torque gains by replacing your restricted factory car exhaust system.

The B&B Exhaust Audi S4 Non-Turbo V8 Exhaust 2004-2018 for your 1998 Audi S4 is a great way to increase horsepower and torque gains by replacing your restricted factory car exhaust system.