I've done my own cast bullet designs up to 180gr for suppressed subsonic loads, and can run those up to ~900 fps. I like my 170gr design a bit better though at about 950 fps.
Other than quiet suppressed loads though, I'm not sure I see a whole lot of value in trying to turn the 9mm into a slower skinnier 40 S&W. That's not where the 9mm's strengths are.
