Radio "Squelch-type" Noise

Have an unusual problem with a new radio, an ICOM panel mount. Nothing
wrong with the radio, but I'm getting a squelch/static noise at certain
times. It is worse when both mags are on and when the engine goes from
about 2200 rpm down to idle. It is less on one mag and practically
non-existent on the other. It sounds like someone is breaking squelch.

A local radio-guy suggested 2 new "P-leads?" I wonder if he meant
capacitors, which is what the previous owner suggested replacing.
Spruce and Chief have mag noise filters at about $45 each. AmeriKing
has a DC filter for over $100. I ordered 2 capacitors for about 10
bucks each, but there are others for close to 50 bucks each. Anyone
have any experience with this stuff? I figured if I'm going to waste
my money, I may as well try the cheapest things first. Radio is in a
craft with a Lyc O-360 w/Bendix mags. Thanks.