Had mine installed about 10 days ago. Same 18psi, except I can drop it to 13psi for a few seconds on WOT now before it goes to 15. The first full tank after install and driving the devel out of it, 10-11 1/4 track runs, playing with the new turbo and boxes up all the way about half the time my mileage was above normal driving mpg. It should have been 2+mpg lower with the type of driving. I do believe the FASS had a hand in that.