a standard spark plug should last 10-20K KM...those better/performance type should last 30-50KM....
Spark plug is wear and tear part...
Also life span of spark plug depend on your engine condition...if your engine makan engine oil / wrong tuning then your spark plug will wear out faster.
can someone tell me how to connect the hks fcd between safc ? which is 1st and which is second and then last is to ecu? pls guide me to the further , tq very much