70 Challenger vinyl console replacement

I am getting ready to replace the vinyl decals on my center console and door inserts on my 70 Challenger Vert.
Is it better to go over the top of existing or remove the old vinyl?
What is the best way to remove the old vinyl if that is best?

Remove the original vinyl first. I had good luck removing the old vinyl with a small steam cleaner. Others have had good results with a Goo-Gone type product.

heat gun sure helps.. or hot hair dryer

Razor blade and Goo Gone, just like any sticker.