If you're really at about 5500 through the traps a switch to 4.10:1 will help you... Can also tell by your mph vs ET that you could use some more gear. I would normally suggest a shorter tire since it's easier to change tires than gears unless it's a big change but seeing as how you're already at 28" I donn know if you want to go smaller... A 4.10 should get you a better short time and probably a few tenths off ET. But if you're trapping at 6000 you don't want any more gear

-Chris