Probably because it was dislodging all the cack that's built up over the years, and you sure you weren't driving it just that little bit harder to see if it made a difference ? 
It was wierd, Usally when i floor it it picks up slowly to 3,000RPM then flys to the redline at 5,000 RPM, Then i shift and the tach goes back down to 2,000RPM where it will slowly work up to 3,000RPM then start to fly up again.
However on the optimax is seemed to lower the whole thing down by 1,000RPM The car would kick and fly from 2,000RPM all the way to 4,000, Then start to slow up to 5,000, Its just like it moved the torque a lill
