I've only ran two tanks through it since I installed it, and it seems to be working. I eyeballed the height when I built it, and made it slightly too tall. It sits about 6" behind the leading edge of the factory air dam, and has a curve that has it meet the corners of the stock piece. I have not installed the filler panels between the factory part and mine yet, since I wanted to see if it needed changes.
I think I will nudge it forward slightly and trim it down a bit, but I'm fairly happy with the results.
The first tank with it installed got 18.5 MPG, and was mostly freeway. The second was 16.5, but was almost all city, with me hauling around some bricks and a small box trailer full of tools.
I'll post pics later, I'm on mobile right now, and they are on the laptop. Thanks for your advice everyone.