I've been eyeing the tweeked manifolds for the same reason. I'd like to keep it stock looking but get a little better airflow. The site says that the stock intake may or may not fit though...

That looks like a 3rd gear pull, based on the MPH. It is best (IMO) to use 4th gear as it is a 1:1 ratio. Nice torque gain though... the low end looks great!