Actually not true. The JB4 app used to be bad...and it was pulled by the dev. It has just recently been put back.
Terry disagrees with that.

The sampling rate from OBDII apps and cell phone CPS just isn't fast enough to be accurate. It'll spit out a time that you can compare to previous times but ultimately neither of them will be true.
Fwiw, he's said we can run Map 3 with high quality fuel (I forget the exact verbiage). A lot of people are using it with regular 93 octane. I did it for a few weeks and didnt have any issues. Terry looked at my logs and said they were good to go. But since I'm RWD Map 3 gives me huge traction issues that result in my car being slower than Map 2. Speaking of traction, have you toyed with the boost by gear settings yet? Are you RWD or AWD?