For anyone looking for a 987 MAF housing adapter sleeve (3.25" OD 3" ID) I found this on eBay that might help. The pvc-welt link wont work for us US folks (
AFAIK).
https://www.ebay.com/itm/16mm-200mm-PVC-Inner-Diam-Equal-Water-Supply-Pipe-Fittings-Adapter-Connector-/174808609002
Hope this helps someone. Im in the process of sorting parts for this upgrade now.