Pilot Sport 2's were the pinnacle of tire technology in their day succeeded by the current Super Sports. They will likely wear out in about 20-25000 miles brand new on the Mustang when driven spiritedly and should be quiet and smooth throughout their lifetime.
What is most important is their age and how they were stored. Look at the DOT label for their date of manufacture, it should read XXXX XXXX 46 09(alphanumeric with the last 4 digits being the date in weeks/year). Also make sure they were stored indoors because direct sunlight will cause dry-rot surprisingly quick.