Bob, the best I've found is to simply bust the old ones out, enlarge the
holes, and install the longer louvers.

I haven't done that -- yet -- but only because my original louvers are still
hanging in there, barely.

I *do* have experience cutting the holes for these louvers, though. With a
dremel tool it's not too bad, in a tedious sort of way, and if your plastic
is not too ancient and brittle. If it is, you'll find that it will simply
shatter when you try to handle it.

At which point, you might as well replace the whole ceiling plastic air
duct/light/speaker assembly. Doing this took me about 8 hours, although I
could probably do it in four now.

By the way -- check out the Cherokee Pilot's Association website (and
"Cherokee Chat" -- their members-only chat room) -- it is great for this
kind of stuff! It's at www.piperowner.com .
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"