Lynn, here are two pictures of the inlet to the 48 Weber.  The K&N filter is three inches deep.  Is this enough clearance for airhorns on the inside of the filter?  The 48 mm throats and the filter base appear to be held in by the nuts and small metal pieces on each throat.  Would the airhorns just be bolted onto the studs by the throats.  Do the throats require special tools to remove them, hopefully there will be no need to do this, but the filter base is under these throats.  JohnD

 

I like Webers, even the DCOEs. The throats, (chokes or venturis) pull out after the accelerator pump jets and boosters are removed. The booster may have a small flat brass screw in the body (outside) to apply pressure to the booster to keep it tight. Those clamps push in on a ring that pushes down on the top of the booster. The air horn will/or may have a similar piece already on the horn that does that. The nuts are like 8MM.

 

After market air horns have a flange with a hole for that stud and nut. Stock Weber horns have a small rib around the base and those little clamp things just push down on that to hold the horn in place. Stock Weber horns may fit this just fine. Larger aftermarket horns are probably too big.

 

The filter (A K&N washable) is on the small side for continuous 6,000 RPM. You could buy a taller element

or use two stacked and Prosealed together. The horn should clear the cover by one horn diameter. More clearance is just barely detectable on the flow bench. The K&N flows a bunch more than a similar sized paper element.

 

The race car filter element is 6 inches tall and 14 inches in diameter. It cannot be too big.

 

 

Lynn E. Hanover