I was looking around on NAM3forum to find the best place to post for EOI for the carbon reproduction of the stock plenum and saw some group buys for carbon parts from a supplier in Germany. They don't have a reproduction of the stock plenum but they do have a more CSL-style intake that reduces down to what could be a MAF-compatible end. The description says it is "simply exhanged for the original part". It looks a bit long and on the wrong angle to line up with MAF in its stock location? See the link below. Is this a possible solution? I still like the simplicity of a carbon stock plenum, but this could be worth considering too (if it fits with the MAF):
https://carboproject.de/en/collectio...box-bmw-e46-m3