What are facts about the F4 tornado?

Facts about F4 and EF4 tornadoes:

• In assessing tornado damage, the most difficult difference to determine is between (E)F4 and (E)F5 damage as both involve structures that are completely destroyed.
• The winds required to do F4 damage were originally estimated at 207-260 mph. However in the 21st century this estimate was found to be too high an was lowered to 166-200 mph for an EF4 tornado.
• Although F5 and EF5 tornadoes are generally the most destructive, several F4 tornadoes have temporarily held the title of costliest tornado in U.S. history. Most recently the Tuscaloosa, Alabama EF4 tornado of 2011 held that title with damage totaling $2.2 billion until the Joplin, Missouri EF5 tornado beat that record three weeks later.
• Even though F5 tornadoes are generally deadlier, more deaths in total result from F4 tornadoes because they are more common.