Replace stream if condition is met

I'm trying to avoid collecting the payload. 

I actually realized I know exactly how does the payload look like without my insert... So i made a simple stream::expression that adds to the known payload. 

something like this:

when HTTP_REQUEST {
    STREAM::disable
    HTTP::header remove "Accept-Encoding"
}
when HTTP_RESPONSE {
    if { [HTTP::header exists "Content-Type"] && [HTTP::header value "Content-Type"] contains "text/html" } {
        if { [HTTP::header exists "Content-Length"] } {
            HTTP::header remove "Content-Length"
        }
        STREAM::expression {@"module"></script></body>@"module"><script type="text/javascript" src="/secfense/js/eru.js"></script></body>@} 
        STREAM::enable
    }

}