Installing new carpet, need advice

[UATahoe]

First off, this forum has been awesome! It has provided a ton of information for me and my father as we have just recently started restoring an 87 R10. I have posted a few questions so far and have received a ton of advice and information.

Now for the task at hand. We just finished pulling up the carpet and are planning to put down the new carpet kit ourselves. When we pulled up the original carpet, the carpet pad portion in the drivers and passengers floor pan stayed glued to the floor. The black backing on top of that also remained. So the actual carpet was all that came out. All of the padding and black backing is adhered really well to the truck. Should i go through the effort of removing this, or should i just leave it in and install the new carpet on top of it? Also, i am guessing that if i leave it then i will not need to order carpet with the mass backing? Would ordering it with the mass backing just add another layer of sound proofing and still install nicely? Thanks for the feedback guys. I am going to try and get pictures up tonight of our progress.