Unlike many rev limiters which simply cut off the ignition spark, the MSD Soft Touch Rev Control uses computer circuitry to drop one cylinder at time and then fire that cylinder on the next cycle to prevent fuel from loading up the plugs. The result is very smooth rev limiting action that holds the engine at the selected rpm limit without backfires, extreme roughness or engine damage. The rpm limit is adjusted with plug-in modules and 6000, 7000 and 8000 modules are supplied.