Warning to those post 03/08 build 135i owners wanting to tune
There is reasonably accurate information that BMW AG has changed the ECU/ECM on 135i cars starting in March, 2008. This new Siemens ECM v81 (v80 prior to March, 2008) incorporates new hardware/firmware and reportedly can detect all ECU re-flashes and most piggyback tunes.
In conjunction with this factory change in ECU hardware and software, there is also good information that BMW is preparing to take a less understanding position regarding warranty work that might arise from any tunes/mods.
Those of you planning to mod you car may want to bide your time until the diffences in the v81 are more clearly understood and/or until BMW makes its intentions better known.