Karbonius have added a 'pillar' to the plenum to reduce the flex and re-tested. Volume appears to be unaffected. Possibly there's a slight change in tone? Video below.
To plan a production run, Karbonius are asking for people to indicate if they intend to buy one. I'll start a list in the next post. Don't forget that Z4 people and post-10/2004 M3s will need to buy the old rubber couplings and matching clips for the plenum side (parts 3 and 4 here
https://www.realoem.com/bmw/enUS/sho...diagId=11_3517. Or, you can buy the Turner silicone coupling kit, which is quite a bit cheaper than buying new OE parts.
Karbonius plenum with extra reinforcing:
https://youtube.com/shorts/-6nf6_zrNxY?feature=share
Karbonius plenum without reinforcing:
https://youtube.com/shorts/NtCRPz1705A?feature=share