Half a psi isn't enough to bitch about. That may be just a variance in the gauge calibration, flexing inherent in the tubing, pulley variance, etc. You're right where you should be, imo. Peak numbers will vary based on the dyno, but since you dynoed previously, this makes a good comparison to your NA power level. Keep in mind the percentage improvement and the shape of the curve. Note the comparison:
Bone Stock M3 with Intake:
Supercharged M3 @ 6.5psi with other mods:
