um I don't use ! in my triggers for the most part cuz of conflicts with anope. I mostly use @ ,but if you want to use ! just change the @ to a ! or if you want to use both @ and ! you can do..

for !

 on $@*:text:/^!peak$/iS:#:

for @

 on $@*:text:/^@peak$/iS:#:

for either or

 on $@*:text:/^[!@]peak$/iS:#: