What's This? And how important is it Lol
 

2000 Z28 - Noticed this thick piece of rubber ripped almost completly through. Pic is taken from drivers side exhaust tip, inside of rear wheel is on left, my finger is pushing the Ripped rubber down, if I remove my finger it snaps back up. What is it and how important is it? Looks like it been trashed for some time. Lol

http://i589.photobucket.com/albums/s...t/8e5cb646.jpg

Looks like the factory seam sealer.

Looks like it might be the bump stop cant really tell from that angle but thats the only large piece of rubber in that location that i can think of. It keeps the rear from slamming into the underbody of the car from a hard hit from a pothole, train tracks etc.

Seam sealer huh? At least you got a name for it, but I'm guessing it's not. Thanks for playing. Lol

Anyone else have any ideas?

Looks like the factory bump stop to me. That's very common. My passenger side bump stop is in pretty bad shape. :(

This sounds like the winning answer! Thanks man.

Bump stop. Mine looked the same w/ 85k miles. They just rot. Plenty of vendors sell them.