If one were using a carburetor OR if we weren't priveleged enough to view the top side of the engine thru the rear window...
I'm most definitely with Chuck on this one, Bill. 'Tis only my 2 cents, but to have a TWM or Weber set up and then not be able to enjoy it visually as well just doesn't add up.
I recall a thread about an air filter box developed by one of our own some time back. It was a see-thru box made of lexan/plexiglass/perspex, with two filters mounted, one on each side of the box. While it looked to be a fair bit of work, the finished product was 'clearly' a winner.
Nonetheless, this is well worth considering for some applications - TWM wouldn't have developed it if they didn't think they had a market for it!
Regards,
T.