Are they going bad? if so, what leads you to believe this? how many have you been through? have you tested your whole ignition system (source coil, pick up  coil, ignition coil, valid grounds and connections, any non-oem tape on the harness?). Any and all info helps in these situations. Ive seen too many people replace CDIs with out it solving their problem. Im not busting balls, just trying to help out.