I noticed the biggest difference in trying out cars in the 20 miles of Willow career race. Handling is better and lap times are quicker for me when I add a flat floor. Try it - take a car that can have a flat floor, tune it but leave the floor as stock. Enter the 20 miles of Willow event. Then add the flat floor, re enter event and see how it feels and what your lap times are. Depends on the track I guess too - you need good downforce/grip at Willow on sports tires!!👍