what type of bench are you using?...if it is a Superflow(or Superflow based design) there is no need to correct....a properly calibrated Superflow will provide the same results regardless of altitude, humidity, temp etc...they are basically self correcting. If you mean flow @28" mathematically corrected for 60" then the number should be nearer
660....450@60" mathematically corrects to
307@28"...I realize that the higher depression may/will cause conditions in the port that may/will change flow levels just wondering exactly what you meant?
