I, for one, am confused as to what you're question is referencing. When you indicated you wanted to install a "heavier" carpet, do you want to install a carpet that is more dense with the same height, or are you looking at adding height through thicker padding and/or higher (thicker) carpet? I would probably go with the more dense carpet--plush carpet--rather than adding more height. Then, I wouldn't feel concerned about the slide's impact on the carpet. It sounds like a great modification!