I've installed the safari snorkel to mine.
Install is easy if you take your time and follow the instructions, it comes with a template to stick on your fender that has all the necessary holes marked on it so it's just drill and bolt on really.
I found the hose under the fender that joins the snorkel to the original air intake a bit short in th over lap so I replaced mine with a longer bit of good quality rubber hose, other than that the kit has all you need in it.
I went to a bit more effort than most to seal mine properly seems it spends alot of time in rivers, instead of using silicone I used a 3m product called scotch weld
DP 8005 which is more like a cement that will bond rubber to LDP (what the snorkels made of) . I did silicone it first then tested it in the river but still found water to be getting in some where with the silicone that when I took it off and 3m'd it all up

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Don't for get to seal any drain holes in your air box etc I put a small tap in mine so I could open it and check if any water is getting in and drain any rain water that might find it's way in.
I only fitted mine for the fact that I play in water alot and was not looking for the ram air effect to increase HP which I haven't noticed any way

so I'd say if you after extra HP you won't find it with a snorkel.

Cheers Shane