how big can sigs be?

pretty big

Or rather small

The signature is defined by the subject.

Does size really matter?

I believe you will find what you are looking for here: Signature And Avatar Dimensions

You will see on step #2 that the maximum dimensions are 350x110 and the file size is ~ 56-57Kb.

I hope I could help.

This post was edited by betoggc on May 23 2014 08:24pm

lol what is this nonsense

Before helping make sure you know what your talking about. The max size is 400x150 and 70kbs.