Yes you're right about the airboxes. What I meant was that it depends on how the open airfilter is installed. Mine reaches out to the air intake grille. That can't be worse than the box which had its "snorkel" in the same location.

I never expected to add hp with the K&N. I just hoped for some more sound. I did get more sound, but far from as much as I had hoped for.

My .02,

I wouldn't mess with the Krap&Noise filter just for improved sound. I'd go with different pipes if it's important.

I didn't put a cone filter on my 87 for hp, I put one on because the original box had the back side clip craked from some hammer handed wrench and it wouldn't seal to the filter properly. I did take the time to "port" match to the mass air sensor though.
And who in the porsche community drives their car down dirt
roads?

Keith Epperly 87 slant nose carrera cabriolet turbo look