The text-to-speech service has a speaking rate option that goes from slow to fast. But the fast option is not fast enough (its 300 words per minute).
I just tried to create a service. I simply dragged the "Speak text" action, saved it and tested it. It seems that my new service still relies on the speed option specified in the preferences.
Is there a way for me to tell it something like "render speech at 400wpm"