Is it possible to re-negotiate?

I received a meta offer that was pretty average and negotiated to around 178/410/35. I was pretty satisifed at the time but after doing more research I realized I left some money on the table.

I have the offer but haven't signed yet, is it possible or too bad mannered to re-negotiate?

Aiming to bump signing by 30-50k if possible and base by 2-7k.