Ya know I thought about this a long time and refused to believe there wasn't an easy way
that would not harm the horns and that would take less than 2 hours...
anyway that's how I am..
I'd rather take two years to figure out how to do it in a few hours.

I was on the right track but didn't think it through.
The pipe foam in Lowe's/Home Depot is okay.
Here's what I did:
1) take a dowel with foam and first cut a slice to use as a base...
this was what I finally figured out
http://www.steevee.com/images/foam1.jpg
http://www.steevee.com/images/foam2.jpg
2) apply it to the edge...
http://www.steevee.com/images/foam3.jpg
3) cut/shape attach the pipe foam to the edge plus the additional foam edge
http://www.steevee.com/images/foam4.jpg
http://www.steevee.com/images/foam5.jpg

The effect is appreciable...sounds like horn blare diminished. It sounds MUCH better.
This'll cost ya 10-20 bucks...hope someone finds this helpful!