sku: 101-81s ESS E-Flash N54 "is/1M" spec ECU Performance Software ESS E-FlashFlash N54 "is/1M" ECU software is a result of extensive testing and exact calibration of ECU parameters to allow conservative performance gains on an otherwise stock car. The ESS 335i software is developed and tested in extreme heat in the... MSRP: Now: €574.77 Choose Options Compare Selected