Richard- The stock plug for the 5kcsq is the Bosch W7DTC. It is a 3 terminal plug, so it works better than the split fire! They retail for under 4 bucks and can be had at most import parts stores. I replaced my plugs with the 3 terminal ones and I could really notice the dif over the single terminal. gluck Dan Hamren Foster City Ca 87 5kcsq wagon 147k miles S4 suspension