Chas- I didn't mean to imply that it didn't work (sorry if you took it that way). I was just curious as to just how much air could be coming in from that tiny scoop. If you have noticed performance gains then it must be doing something right!
Prior to building that setup, did you ever try just going with a larger air cleaner & filter? Just curious.
I had a Moroso 14" on my side oiler for awhile and it breathed MUCH better than it did with the little 8" S&H and TP. Whenever I ever went to the drags I would run with the Moroso setup. Couldn't tell you what the difference was in my times though because I never raced it with the S&H and Turkey Pan on the engine. All I knew was that the engine ran MUCH better.
When I had my 70 Chevelle SS I screwed around with the hood a little (what can I say, I was young). I removed the cowl hood and rubber gasket around the air cleaner and replaced it with a copy of the 67 Corvette "stinger" hood. The small forward facing scoop never gave the engine the same amount of cold air that I was getting with the cowl induction setup, so I eventually switched back. It was amazing the difference in the way the engine performed.
Most of these types of things are all trial and error. Try different setups and go with what works. If your setup works for you (and obviously you're happy with it) then that's all that counts.