I used the $21 Spectre tube. My whole setup is based very closely on srmitchell's thread
http://www.jeepforum.com/forum/f11/my-attempt-cowl-snorkel-727684/
Frankly, I was intimidated by piecing together a solid tube out of PVC. My work with PVC is exceedingly limited and all the geometry seemed overly complicated, so I opted to use a universal intake tube based on a TV commercial I remember as a kid for a product which I think was called "Flex Jars." :laugh:
AutoZone.com | Air Duct Hose | Black air ducting
I removed the air box, cleaned it up and used the tube to get a rough idea of where it would need to go. I marked and drilled a small hole in the center of where I wanted to place the tube.
I cut a strip of plastic and drilled two small holes in it 1½" apart as my template for the hole.
I used the drill bit as a hub and drew the circle I would cut with.
I have a pneumatic trim saw I'd planned to use but my compressor is at my parents' place so I used what I had on hand, which was a simple coping.
I drilled a ¼" hole as a starting point and reassembled the coping saw with the blade inside the hole.
I proceeded to cut out the air box with the coping saw. When done, I used a Dremel with a sanding wheel to smooth the edges.
I again used the tube to determine a rough placement and used my template to draw the circle which I would cut out.
This is the hole one everything was cut out. It turned out quite ragged as I used a Dremel with small cut off wheels. I smoothed it out with a grinding wheel before installing the tube but I was excited the hole was done and forgot to take a picture.
I mounted the tube up as high as a could so that the base of the cowl would act as a dam to keep water from entering the intake tube.
As srmitchell had warned me, this did result in the tube making contact with a rib on the hood but since I used a flexible plastic tube, I don't think it will be a problem.
And much of my reasoning behind adding this mod to my relatively stock rig is because a photo I saw of one of my fellow club members with a significantly bigger XJ than me in a water crossing I know I'll be facing soon.
I still have to seal up the front of the box and the weep holes as well as secure the box better. There was some creative fastener use employed by a previous owner I didn't bother to deal with today.