Lower air box pipe diameter?

[JTaylor2005]

Hi guys, Want to try and fit a bigger smoother cold air supply to my air filter box. Looking at the one currently on it seems to be made of crap material and also has a nice tight 180* bend in it. I am tempted to build up an intake from silicon hose and pipe and fit it to the current bottom intake hole on the air box. Any ideas what diameter it is?

Thanks

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Changed my mind. Looking around there no where good to put a better colder/ higher flowing intake without most likely filling my engine with water haha.