[wilf leek]

Interesting thread.

I too am limited for space under the hood, and have the Cobra oval air cleaner.

When on the chassis dyno, we did check for differences with and without the original paper filter - little to see. Certainly the AF ratio stayed the same as well.
I now have a K&N filter in there - the #1963 I think - anyway it's around 1 3/4" tall.
In theory, according to the established equations, I need a 14" dia 3" tall filter, but it just won't fit, and crossmember issues mean I can't drop the engine either.
Still it seems to do just fine with the filter I have. I hooked up a vac gauge and at WOT/high revs, there appears to be little manifold vacuum - about 1" from memory. Would this indicate that the filter is not, after all, too restrictive?