What hook to use for modding signatures?

[Citizen]

I need to do a query to a non-vbulletin database and import some information for each user right before their signatures. What hook would I use for this?

[itsid]

right "infront" of a signature is directly after a post.
So postbit_display_complete and there adding a

$post['message'] . = '<hr />'. $whatever_you_querried_from_the_other_database

would add a horizontal line (hr) as a seperator and whats ever in the db-result directly after the post, or directly infront of the signature ;)

'sid

[Citizen]

Where do I execute my php code?