M4 (F82 & F83)

Most experienced owners fit a pinned crank hub and aluminium charge pipes before adding power, then an intake and a stage 1 tune. Sports-cat downpipes, an exhaust and improved cooling follow for stage 2. For handling, uprated brake pads, quality tyres and either lowering springs or coilovers transform the car, and a full geometry setup afterwards makes the most of the changes.

The S55's factory turbos are commonly reported to support around 500 bhp on pump fuel with a stage 2 setup of tune, intake, sports-cat downpipes, charge pipes and supporting cooling, with more possible on ethanol blends. Results vary with fuel, climate and calibration. Beyond that point, upgraded turbos, fuelling and drivetrain work are typically needed, and a pinned crank hub is strongly advised at any of these levels.

They will fit, and the adaptive dampers continue to function, but the factory dampers are valved for standard ride height, so very low drops can affect comfort and control. Owners wanting to keep adaptive damping often choose a coilover designed for it, such as KW's DDC plug-and-play kit. Cars on passive dampers can use springs or conventional coilovers, followed by an alignment.

Engine, exhaust, brake and most suspension parts are shared between the F82 coupe and F83 convertible. Roof, boot lid and some rear body parts are different, and the convertible's extra weight can mean different spring rates in suspension kits. Check the fitment on each product listing, or add your exact car to My Garage so the catalogue filters to parts that suit the convertible.

It is a recognised weak point rather than a common failure. The factory hub is press-fit rather than keyed, so under high torque it can rotate on the crankshaft, changing valve timing and risking serious engine damage. The risk is widely considered to increase with tuning and hard launches, which is why a pinned crank hub is a standard preventative upgrade on modified M4s.

In the UK, a remap and most performance parts must be declared to your insurer, and not doing so can invalidate your cover. Warranty is at the discretion of BMW or the warranty provider, and engine or gearbox claims may be refused if tuning is found, even after the software is reset. Read your policy and warranty terms before modifying and keep a record of all work carried out.