Should I add more padding to my racing seats?

[The_Domm]

So I got my Z32 a while back. It's a 95' but it had new-ish Cipher racing seats that were put in before I got it. The problem is that the padding on them has given up a lot and I don't really have the money to get new racing seats. It feels like I'm sitting on cardboard. I was thinking of adding more padding to them myself and just wanted to know if it's safe to do that with bucket seats. If so what kind of foam should I use?