Some of the fullsize have them stock. They can be picked up at the salvage yard with the grommet for under $5.
I thought it would be a good idea to know when there is some restriction in the aircleaner.
With the FIPK, some dirt actually helps to filter the air by trapping more dirt , if that makes any sense?
But in this dusty , dirty , high desert environment how do you know when it is getting too dirty?
I had to go to the salvage yard today to pick up a replacement indicator for one of the fleet rigs, and thought it would be a good idea to have one on mine too.
So here's what I did-

I drilled the 11/16 inch hole for the grommet and installed the indicator.
"Easy as pie" and another low buck mod that would work equally as well installed in the stock or modded air box.
One more thing. I still have the IAT relocation wiring that I made for the stock box. Since this grommet is also the correct size for the IAT sensor, when I get Autotap , I will be able to swap the IAT and the Restriction indicator to see if there are any gains.