I know another guy who tested some Stealths on a SuperFlow 600 Bench at 28" with portflow analyzer 3.0 software. His results were as follows...
.600 lift, out of the box heads.................... Intake- 254.4 cfm
Exhaust-198.3 cfm
.600 lift, with bowl blending and mild port work...Intake - 282.5 cfm
Exhaust- 223.7 cfm