good idea basti..

but why avatar smaller?

not larger sig´s, only to get better quallity

I don't like the idea, from what I've seen most people use avas that are 20kb or less, so limiting the avas does no good as 50 kb isn't hit that much as it is...it would basically just increase the time to load pages.

Well, I can understand the underlying reason. And technically, the site load won't suffer, as the total KB limit of signature plus avatar remains the same.
But my fear is that increaing the KB limit for signatures would lead to much more annoying animated signatures. Personally, I really don't want this to happen.

yes!

but i want 128k

no ! its fine now !

I would say no just because it will ne ver happen.
I think you can't imagine how it will be hard for the server if evryone have a biger sig.

i'd just say, ava + sig together shouldnt exceed ~130kb in total.
but your idea would be also fine for me.

It isn't that I don't like the idea, I just don't see need for change since not always higher kb size is going to equal more quality in a signature although in some cases I guess it could especially for animated & transparent png signatures since they general have higher kb size than anything else.