I was told by Hypertech, that the more you add the better it will work, and I believe the timing is advanced in the tune. I haven't changed any of the limits, I don't drive that hard or fast. I got better mpg gains with the 87 tune, but I also drove for better mpg. I'm currently in the high octane tune and the mpg is about the same, mostly because it fun and I've been on the beach 1-2 times a week. I stopped traveling so I don't have good mpg numbers for the high octane tune, but around town its about the same as stock.
I definitely love it and think it's worth it. The high octane tune is great and a lot of fun to drive for about 6-8$ a week more and the 87 tune with the WOT restriction gave me 35-40 miles per tank more. (about 20-25 miles more without the WOT restriction) I think its worth the money for removing the WOT restriction alone.
If you drive for mileage, you could get your money back for sure, at 35-40 miles per tank more and using a tank per week it's about 2 gal per week savings and at 3.10$ a gal currently, you could save 300.00$ or more a year. This also depends on your consumption and fuel cost. I thought all I would use was the 87 tune for mpg gains until I tried the 93 tune.........it happens.
All of this information was in the thread, but here it is again anyway, hope it helps and it definitely has my approval.
Anthony