RS4 - B9 (2017+)

Many owners start with styling and feel: a front splitter, side skirts and paddle shifters change the look and driving experience without affecting the drivetrain. For performance, a Stage 1 remap of the 2.9 TFSI is a popular next step, often with gearbox software for quicker shifts. Heat protection for the hot-vee turbos and fresh, high-temperature brake fluid are sensible additions on any car used on track.

The 2.9 TFSI is a well-engineered engine that is also used in Porsche models such as the Panamera 4S, but tuning increases heat and mechanical stress. Keep oil and coolant fresh, use quality fuel and manage under-bonnet temperatures, as both turbos sit in the vee. Known areas to check across the EA839 family include water pump leaks and PCV valve faults. A healthy, well-serviced engine with sensible software is the best starting point.

Engine, gearbox and many drivetrain parts are shared, because both cars use the same 2.9 TFSI, eight-speed tiptronic and quattro system. Body parts are not interchangeable: the RS4 Avant has its own bumpers, arches and rear end, so splitters, diffusers and spoilers must be RS4-specific, and exhausts can differ too. Check the fitment shown on each product, or save your RS4 to My Garage on R44 to see compatible parts only.

Not always, but many tuners recommend it. The eight-speed tiptronic is a torque-converter automatic that generally copes well with tuned torque, and gearbox software can raise torque limits, quicken shifts and improve response in manual mode. Ask your tuner whether their engine calibration is designed to be paired with TCU software, and keep up with gearbox and quattro fluid servicing on a tuned car.

It depends on the kit. RS4 B9s have either standard RS sport suspension or the optional RS sport suspension plus with Dynamic Ride Control (DRC), which hydraulically links diagonally opposite dampers to reduce roll. Many spring and coilover kits are specific to one setup, so check the listing carefully before ordering. Some owners with tired DRC dampers choose coilovers instead of a like-for-like replacement.

Yes. In the UK, insurers expect every modification to be declared, including styling parts such as splitters, spoilers and wheel spacers, as well as remaps. Failing to do so can lead to a claim being reduced or refused. Keep receipts and fitting records, and if the car is under an extended warranty, check its terms, as claims linked to modified parts or software may be excluded.