I've been running the regular tune for a couple months and saw a modest difference ... certainly helped on highway mileage if I wasn't going over 75.
I just switched to the performance tune today and man ... it really woke up. Can feel a big difference in acceleration from a stop and while cruising on interstate. Doesn't feel sluggish ... no if I can only keep my foot off the pedal I might not see much a mpg difference.
Lmao, I just moved back up to the 91+ tune and man it feels so sweet, just price on 94 octane here is a killer, so I might move back down to the 87+ but I got a full tank to play with, hopefully prices will go back down soon.