http://www.excellgtp.com/stuff/m90/
This information is for the GenV M90, so it's about 15% better in all categories over the Gen III. But you'll get the picture.
The short story with your blower is: You can run down to a 2.50" pulley on it with is approximately 18,000RPM. However, it gets TERRIBLY inefficient after, say 2.60" which is approximately 16,000RPM. On a stock case you'll will make good gains down to around a 3.10" pulley, after which you enter into diminishing returns unless you have the case S-ported to reduce heat generation. The M90 turns into a heat pump under 3.10" unless said porting is performed.
In all cases, after a 2.60" becomes significantly diminishing. Further, spinning faster than 18,000RPM (2.50") will cut the life of the blower, and it’s bearings, at an extraordinary rate.