you can pick up a spectre oil filter they are adaptive from 2.5 inch to 4 inch od. They have series of rubber gaskets. installed at the base of the filter, you simply pull out a size at a time till it fits.

 

Great looking CAI!! Will you get HP gain no matter the engine size? I am running the 3.7. Also, there is what looks like a vacuum hose on the back of the stock box, does that need to be connected to the new CAI somehow?

 

Where do you get the cable "brace" holding the tube/filter in place. The red cable by the filter in the photo posted in the thread?

 

That is not a cable, it is a piece of 1/4 threaded rod that you carefully bend a half inch at a time. yes I said a half inch at a time in a vice slightly opened wider than the rod. Once you got the rod bent to the 4" dia of the PVC pipe you put rubber hose around it. It takes a little patience but as you seen if you take your time it turns out really nice. I bent both of these in like 5min. Just ask Butch I am master at bending this stuff. If you take your time it will fit exactly and snug around the PVC. Just remember to leave enough straight to fit through your mounting bracket. As far as a K&N part number don't know, both Butch's and mine are Spectre and can be purchased at any O'Rieley or Auto Zone stores. They do make several different colors and styles these are the biggest and they do have several rubber rings in them to fit smaller pipe if you want but 4" is the largest it fits.
As far as do these things work, flat out YES. I have had Spectre on 2 vehicles now and notice better fuel mileage and HP in both. Seemed to help my 99 Dodge Ram more though. None the less they are fun to build and sound crazy. Have fun building them..
One more thing I would suggest is to dry assemble all the part and mark with a sharpie at all the joints to line them up when gluing. Puller out glue it and paint... Be sure to send some photo's of any improvements to the design.
Hope I answered all your questions.

 

Did you do anything special with the PCV valve?

 

This needs a youtube link so that we can hear the new sucking sound! I know with the mandrel bent aluminum intakes, half of the noise is the resonance from the "trumpet", should be interesting to hear what PVC sounds like!

 

pcv valve stays put, it is way up by the tb in the hemi's

 

The PCV valve is in the oil filler neck right? If so, what do you do with the tube that used to go from it back into the intake? Do you just leave it there with no hose?

 

or put one of those little air breather things on it?

 

Just some really good info on cold air intakes here. This is direct from the Spectre web site. Very cool read....
http://www.spectreperformance.com/profab/