IMHO that ecu is not worth it. There's no plug'n'play alternative ecus to that old shit.
Find 557T/558E (M3.8.2) map packs for example, you should find everything you need in those.
Better to swap or re-pin wiring loom to M3.8.3, which is easily flashable.
Even better, swap loom and ecu to newer ME7, so you at least have good logging solutions.
Because there is no plug n play alternative it is worth it to tune it for a bit more time. Most of the logic is the same as in M3.8.3.
If you need more load than 12.75ms then adjust the maf constant, if you can't find it downscale the maf -> it is a hack but its the same thing. If you downscale the maf too much the idle controller stops working correctly as there isn't enough resolution of airflow for it.
Again it is a HACK but that doesn't mean it is not workable for less than 300hp.
M3.8.3 flashing takes 3 mins, to change 1 plcc32 chip takes less if you are not lazy, no need to fully close the ecu, everything around it is plastic.
For the M3.8.2 with PLCC44 chip it is a no-brainer, buy flashable ecu and tune it.
