When I went to install my BHAF and old smokey mount last week i ran into a problem..
On my 91, the intake tube was the same I.D. as the BHAF, so a piece of 4" pipe was all I needed to re-enforce the connection between the two..
However, my 93 has a 5" ID intake, so there is an inch difference between the filter opening and the intake tube.

I searched on here and found where some folks have wrapped the filter tube with tape to make up the difference, but i didn't like the idea of a loose piece of tape getting sucked into the turbo.
I went to a local large truck shop and bought a 4" exhaust connector.. it is 4" OD on one end and 4.35" OD on the other.. I took this to a local machine shop and had them mill out a stub of 5" pipe so that the large end of the exhaust connector slipped down inside it, and then brazed the two together, and cut off both ends so that there is just enough metal for the filter and intake to clamp onto, giving me a 4" to 5" adapter..

The BHAF slips tightly over the 4" end, and the intake tube is snug over the 5" end... I clamped both filter and intake to be safe.
The cost for buying the parts and paying someone else to do the work was a total of around 48 bucks....if you have a cut-off saw and welder , I am sure it would be less than half that...
the first picture is teh adapter and the second is the adapter and Old Smokey Mount after priming them

 

Nice work!

 

Sticky-ed.

 

I used the original airfilter plate to go between the BHAF and the intake tube.

 

I did too on my second 91, but the 93 has no provision for securing the filter to the plate.. the stock filter simply pushes against the plate, and the BHAF woldnt seal properly like that.

 

On the 93's you can take the clamp and loosen it up place it on the edge or high spot of the intake tube and tighten it. the extra 1/4" or so of material is enough to clamp on to the filter.(wix version) I haven't seen any other available bhafs to say for certain this works for them all. But i do agree definitely don't like the idea of putting tape near my turbo or intake for that matter.

 

Canada, thats an idea, but have you ran into a problem with it slipping off?
The WIX filter opening is slanted, another reason i did not trust clamping to it......

 

If your setup will suck tape out from between the snout of the filter & intake tube with a clamp squeezing it together... you've got bigger issues!

I noticed that the cool weather snap here had shrunk the filter snout down and was very loose in the intake tube. Exactly 5 wraps of 3M Tenflex around the filter made it fit snug without the clamp. Once the clamp was tightened, I couldn't pull it off... should be good until the filter needs replacing.

 

My stock air box (91.5 with aftercooler) had a metal ring that formed the lip which kept the intake hose from slipping off of the outlet. The ring wrapped around the edge of the plastic outlet, extending about 1/2" inside the bore and forming a 1/16" ridge around the outside.

A big screwdriver popped the ring right out of the stock plastic outlet, and a little double-sided tape secured it tightly into the BHAF outlet, making the BHAF outlet almost exactly the same as the stock air box was. The intake hose fits right over, and the clamp crushes down on the hose, the BHAF outlet, and the insert part of the metal ring, making a nice tight connection. (The tape is completely covered by the metal ring and out of the air flow; I am sure that it could be replaced by the adhesive of your choice with good results.)