well according to the sound logic breakout board I am using they say to use mach 2. I tried to use mach 3 and I couldn't get it to work but I didn't try too hard because the instructions said to use mach 2

I really couldn't tell you one way or the other. 
I would suggest click tutorials>Documetation above, then download using Mach2 and customizing mach2  somewhere in the pdf it should have the info on increasing stepper speed.

Wes

smr14,
   I have sent you a personal message. A G0 move is a rapid. A G1 is a feed. You can change the rate in the code listed below by placing a f********* in the line of code. This will not increase the rapid speed or override it. The fastest it will move is the amount you have set in motor tuning. I would go with Mach3 as well.

Brett