The best would be a custom set up with the filter located down by the bumper behind one of the brake ducts. A K&N filter with a 6" I/D (Internal Diameter) onto a velocity stack with a 3.5" I/D. 3.5" pipe work tapering down to the O/D (Outer Diameter) of the throttle body a few inches before the throttle body.
A lot of work, and a lot of money. If it were me, I'd be going to a custom exhaust company and getting them to build the pipe work as opposed to using lots of Samco (For example) hoses.
This sort of set up has been proven to make very good gains, even over the likes of a the Gruppe M/Tegiwa intake. Obviously it does run the risk of hydro locking but I ran a very similar intake on my EP3 with a duct right in front of the filter and used it as a daily and never once had any problem, even in torrential rain. Rain itself isn't a problem, nor is spray, but anything that will submerge the filter is. This is going to be circa 4" + of standing water, IMO its a slim chance of happening.
This is the set up I will be going for once I get my RRC fitted XD.