Check out melloroadman's post about a page down titled "Discovery 100 count shot, one fill". He simply put in a lighter spring from a 2250. I think you may have to modify the pressure since the weaker spriing may not have enough power to open a valve with 2200 PSI, but all that means is filling to 1800PSI and shooting to 900PSI.
You can install an HDD, that lowers the FPS by 50FPS.
Finally, you can run the Disco on CO2 and I beliieve you loose 200FPS