@ Creynolds ,
i know this is a old thread but if you're still looking to eliminate the air box and replace it with a 3" connector that holds our MAF sensors i found what you're looking for on ebay for $30 each . I seen some guy on ebay sell 2 Kn&n filters and 2 maf sensors connectors and call it a cold air intake and charge $499 for it , so I started to look around on ebay see what other cars use similar sensors as ours since they have a weird design and the holes where it screws in are off-sided. Anyhow I found someone selling something that looked similar for chevy , i asked him for measurements and it was a boohyahhh moment because it seem to line up perfectly so I bought 2 and got lucky . basically i made the same setup the other guy wanted $500 for and it cost me $200 , depending on what air filters you want it can be as low as $100 . I have a 2011 BMW 750 Msport with the N63 motor same as the 550i , X5 etc ..look up my garage and you will see the pics how it came out and if you're still looking for the 2 adapters then click on the link below I posted and it will take you to ebay ... hope this helped ...
https://f10.5post.com/forums/e90gara...730D21065.jpeg
i used the same type of 3" extendable tube to bring cold air into the intakes...
https://f10.5post.com/forums/e90gara...86C72840D.jpeg
https://www.ebay.com/itm/312449532769
I am a firm believer if you can find a great deal that didn't cost shit you should share it for free with your fellow enthusiasts ...
and here is the same setup for 5x as much:
https://www.ebay.com/itm/303188813997