a little update as got bored last night so decided to build an adaptor for the stock vw MAF sensor housing - one end of the housing fits into the silicone hose no issues but the other end would normally bolt into the airbox and therfore does not have enough space to fit a silicone hose and aftermarket air filter, so a bit of fiddling with Fusion360 and some 3d printing later I got this:


This gives me a good fitting for the 70mm ID hose joiner now, here it is fitted to the MAF housing:


And finally the full assembly with joiner and new air filter: