Running a little lean so Ill be sending off the data files to Justin to see what we can do, but here is the before/after for the m90 and 2.49" pulley:
Stock Roush M90 vs VMP500 dyno - 07 Mustang GT - 426RWHP - YouTube
Stock Roush M90 vs VMP500 dyno - 07 Mustang GT - 426RWHP - YouTube