To do this, you'd have to reprogram the TCM to get the line pressure duty cycle to up the pressure. The transmissions in these aren't like the 'Camaro' of old where a little shift kit with some firmer springs and a different accumulator piston would do the job.

I don't know of any company that is working with the transmission, but you might call Uprev in Texas and see if they have anything. I know they work with the 350Z, Titan, Armada and G35's, so they probably have a better clue as to what's out there.