These add on harnesses attach to your JB4PRO system to enable various functions:The B58/S58 FLEX harness lets you attach to an external ethanol sensor and/or pressure sensor, and is required to use the port injection harness add on. The B58/S58 PORT harness plugs into the flex harness to enable port injection.The Kia 3.3T CPI harness plugs into your existing Kia/G70 JB4PRO harness to enable charge pipe injection (CPI)
