A majority of IS-F I've seen run mid 12s with good tires and some lower pressure or with drag radials. Still 13.39 at that altitude is good for being your first runs. I agree with IS-F Champ, lower your tire pressure so you can hook better or get another set of rims with drags on em and see what you can do but always warm your tires. It's amazing the difference. Would like to see your passes, it is always fun watching others especially if they beat an IS-F hater or non believer lol.