Bilstein B4, B6 or B8: start with the springs

B4 is the original-equipment replacement direction. B6 is the performance-damping direction for a supported original-height application. B8 is designed around compatible lowering springs. These are product families, not a promise that every version exists for your car or that every original sport suspension takes the same damper.

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Record year, body style, engine, drive layout, axle-load information and any electronic damping option. Photograph spring markings and measure present ride height before ordering. A previous owner may already have installed lowering springs, so a standard-looking stance does not prove the suspension is original.

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For an everyday car, decide whether the goal is restoring the original behavior or accepting a firmer response. If lowering is part of the plan, match springs, dampers, travel and mounting hardware as a system. Do not buy a shorter damper merely because it sounds more performance-oriented.

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Allow for worn mounts, boots, bump stops, required one-use hardware and an alignment. Ask the installer to confirm electronic-damping compatibility and any required supporting parts. Manufacturer descriptions establish intended use; they do not establish a universal comfort ranking on your roads.

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