1) While a snorkel can help with preventing water ingestion in your engine, it was designed to help the engine collect clean dirt/dust free air while driving around the Australian Outback. A LOT of other things need to be water-proofed before you go playing submarine with your TJ.
2) A ram-air setup will not work with a snorkel.
There is some heated discussion as to whether or not there is any ram-air effect with a snorkel. There are two sides to it and both have some data to back their points up. If there is any ram-air effect from a snorkel, it is marginal at best.
If you ever plan on doing a lot of rock crawling or extreme tight trails, remember that snorkel is going to hand way off your Jeep and grab every rock and tree it can find. Many guys have installed snorkels only to wish they hadn't.
Having said that, my LJ will be getting a snorkel because it will not be seeing much rocks and super tight trails.
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