So I built a snorkel from parts from lowes and a nice scoop off ebay so I can tell you a few points I learned, it is the second one I did. I built a passenger side unit (See Pics) which mated well with my factory airbox. The nice thing is the unit is mostly out of the driver's view and it interferes with nothing, not even my A/C. The downside is it is very vulnerable to damage. I still went this way on both my builds. The hard core rock crawling community drops the duct down through the cowl and out through the firewall. Most members use the hummer style cap on these and they don't seem to present much of an obstruction. I believe they present a significant potential to leak and they rely on flex style dryer hose. I will not argue that they are way less vulnerable but I greatly struggle with the 4" holes in the cowl and firewall. I will post a link on a very well built one but here are pics of my build. Best of luck.
I have done so much with so little for so long, I can do anything with nothing forever.