This was a mod I had been wanting to do for a while. Its pretty simple, build this for less than $20 with toilet/plumbing parts.
A lot of guys use 4", I went 3" because it fits better and its still almost 80% more air than stock, now we get into filter flow rates, and just what the turbo will need. The stock air intake is good for at least 450rwhp, so this should just help out with a little cooler air at high boost.
To start remove the OE air box (which sucked for me as I have a solenoid for my winch attached to it, at that alone took an hour to unhook).
The going in and out, top and bottom, find where you want to center the 3" hole, and then mark it and start drilling. I didn't have a large enough hole saw, so I did the redneck version, and smoothed it with a drumell.
Next slip the toilet flange thru the hole, it goes at an angle so more grounding was required. And put the bolts in loosely.
The put the box back in the truck and put the 3" pipe into the toilet fitting and adjust it so that it fits the hole in the front of the fender. Then tighten the toilet fitting so that's where it sits. The fender goes in and out a few times in this step. At least its super easy.
Then pull it all back out, and carefully remove one nut at a time and locktite the nuts. Due to the angle they aren't all super tight, as that will change the angle at which the flange sits. There is enough tension that locktite and lockwasher will hold it thou. Put it back in the truck to verify angle, and mark where you want the bottom of the PVC to sit (I bought a 24" section of 3"). I put a threaded slip fitting on the bottom of mine so I can block it off in winter (blowing snow), creeks, or super dusty roads. The only time this mod is really useful is towing at high boost, which normally doesn't happen in snow, creeks, or dusty roads.
Then verify length, and PVC glue that sucker into the toilet flange, and bolt your truck back together.
Since my truck is not my DD anymore I put a shower drain fitting in the flange to keep critters out. I trimmed it so its removable, but wont bounce out. I know it restricts flow a little, but like I said under 99% of my driving the minder never moves. It was also an experiment, if I need to remove it, no biggie.
What I noticed was another degree or so reduction in IAT's, and it takes 2800+ rpms at 32psi+ for my filter minder to move now, and thats with the extra air of a cam. Before the cam/CAI I was able to pull the filter minder down at 2700 rpms at 32+psi. I rarely, if ever, run over 2500 rpms.. so I am very happy with the setup.
Part of the reason I pull the filter minder down at all is the Amsoil EAA189 is only good for about 90% the CFM of the OE 2" filter, and even less than the 4" filter. Amsoil is working a 4" pleat nanofiber filter, that I will go to when its released.
So in the end I am getting more air, its cooler air, and it cost a lot less than the PSM version. I also like how its smooth on the inside, vs the corrugated PSM which promotes turbulence.
So if you have a few hours and $20, this is a great mod!.
Kinda ironic that its called a Home Depot CAI, when I bought all the parts at Lowes!