Abstract: A spark plug RFI suppression arrangement comprises a spark plug having a proximal end at which an ignition terminal is located and a distal end at which a pair of electrodes are separated by a spark gap. The spark plug further has an insulator portion and a conductive case located intermediate the proximal and distal ends. The arrangement further has an ignition wire having an end portion carrying a connector removably attached to the ignition terminal of the spark plug. A spark plug boot is located at the end portion of the ignition wire, the boot being configured to cover the connector and at least a portion of the spark plug. A radio frequency interference (RFI) suppression sleeve is connected to the spark plug boot and is in electrical communication with the conductive case of the spark plug such that interference produced by operation of the spark plug is suppressed by grounding through the conductive case.