Update.....
2005 Lexus ES330:
Engine starts much quicker, better throttle response, idles smooth and quiet. ( like a kitten peeing on cotton.) No noticeable difference in gas mileage.
2006 Pontiac GTO:
Same performance benefits observed with the Lexus, however I have seen a decrease in gas mileage. Before testing I was getting about 15mpg city. Now I am getting 13mpg. Still can't figure this one out yet. I think I may have over treated the GTO so I am thinning this tank out with more gas to see if the mpg number goes back up.

