What size is the stock 2005 AP2 final drive?

 

Search button is helpful here, it's been beat to death, The factory differential for an S2000 is a 4.10.

 

AP2 FD 4.1 stock. 4.44 <- good for AP2 anything more than 4.5 you basically say bye bye to 6 gear( FD4.77 6th gear = 5th gear on stock) I love my 4.77 on my AP2, so fast acceleration and fun to drive. one thing is bad on shorter geart, you on higher rpm on highway and lost 2-5miles per gallons.