set max threads by usergroup in forum

[trafix]

ok heres the deal...

i have a set of forums that contains many sub forums. I want to set a max amount of overall threads that a member can start depending on their usergroup. Say a member of usergroup 8 (max set at 6) has his six threads in this group of forums then he has to delete one before starting another.

This limit only applies to the selected forums, not the entire board.

Any ideas???

Would somebody give me a hand here??