M240i (F22 & F23)

An aluminium charge pipe and a Stage 1 remap are the most common starting points, as the B58 gains a large amount of torque from software alone. A cat-back exhaust and an intake add sound and response, and a sports-cat downpipe with a matching map follows for Stage 2. On the chassis, lowering springs, uprated brake pads and fluid, and a limited-slip differential help the car use its extra performance.

Stage 1 maps on a standard M240i are commonly reported at around 400bhp, sometimes a little more depending on fuel and conditions. A Stage 2 setup with a sports-cat downpipe, intake and charge pipe typically adds further mid-range and response. Past that point, the standard turbo and fuel system become the limit, so bigger builds need a hybrid turbo, fuel pump or port injection, plus extra cooling and gearbox software.

Yes. Fitting a sports-cat downpipe without matching software can trigger fault codes and an engine management light, and it will not deliver the expected gains. Pair any downpipe with a Stage 2 map written for it. For a road car in the UK, choose a quality sports-cat downpipe and make sure the car continues to meet MOT emissions and noise limits.

That is usually heat soak. The B58 uses an air-to-water charge cooler, and after repeated hard runs the coolant warms up, intake temperatures rise and the ECU reduces timing to protect the engine. An upgraded heat exchanger, such as the CSF unit for the B58, adds cooling capacity and keeps intake temperatures more stable. It is a worthwhile upgrade for tuned cars and track use.

In most cases, yes. Lowering springs retain the factory adaptive dampers, so the drive modes still work, although the ride becomes firmer. Coilovers replace the adaptive dampers and need a cancellation kit or coding to avoid a suspension warning. The F23 Convertible is heavier than the Coupe, so check a kit is listed for your body style. R44 shows fitment on every product, and our team can advise on the right setup.

Yes. In the UK you should declare all modifications, including remaps, exhausts, downpipes, suspension and styling parts, as undeclared changes can give an insurer grounds to refuse a claim. Some insurers will increase the premium or decline certain mods, while specialist modified-car insurers are often more accommodating. Many M240i models are now outside BMW's warranty, but on any car still covered, a remap may affect claims on related components.