Up here in Minnesota we tend to use preheat a lot.  I made some out of the
cheapest seat foam around- they always seem to blow away at the most
inopportune time- -20F and blowing 20 knots into the dark abyss of snow
filled fields- but I digress-


Make a simple pattern and cut 1/2 larger so you can squeeze them in.

Michael Smith

Keith,
As for the cowl plugs, Aircraft Spruce sells a do-it-yourself kit
...........