It turns out that when welded, lots of internal stress must occur. When the recip saw blade was cutting thru, it would be "pinched" by the horn trying to close where the blade had passed, and as the blade exited, the first gap snapped shut like "snap". The gap the width of the metal saw blade had closed almost completely. So about a 1/8 inch section needed to be removed from each sectoral fin.

Black tape was used to keep the rtv from dripping out the bottom of the cuts, once dry, it was removed. The horns then went "clunk" when struck...no further mods needed for now...even decided BBQ black was a more fitting finish than bare aluminum...lets the speakers "go away" in a darkened room...Sam