Sound Deadening?

[2Ton71]

Hey everyone! New to the board, but have been in and out getting great information from you all.

I also posted this in the interior section.

I have a question about installing sound deadening material. I went with the eDead 45 peel and stick type material and have a general idea of what to do.

My truck has the factory deadening pad on the firewall area under the dash. What should be done with this when I get around to deadening the firewall? Leave it in place and put the new material on top of it, or do what I can to take the old material out? It would make more sense to take it out, put the eDead on the metal, then reinstall the pad. That pad looks like a big pain in the *** to take out.

What have you all done?

Thanks.

Andy