You know I don't know for sure. With my stock gears (2.73) I topped out at 122mph in 5th. Now I have 3.73 gears and I still top out at 122mph. I too had similar results at the track. Except I didn't go slower just no change from previous results. I am thinking the stock H-pipe and catback are bottle necking the power. A drag racing suspension couldn't hurt either.
wait I think I got it...there is a code on the driver door jam that tells what option rear axle you have correct? under the "ax" on the driver door jam my car says the letter z this means I have 3.08s stock correct?