I have had the K&N cold air intake on mine for about 2 years now. Yeah, the sound is cool, Ive been asked if I have an exhaust system because of it (which I don't). As far as performance goes, my butt dyno feels a little better acceleration when you get on it at highway speeds, but nothing much more than the factory air box. Other than that it doesn't do much. Water is a concern for me, being that I did have it stall on me going through a rather large puddle once but luckily not much got into the intake and it started back up. After that I ordered the pre filter to help block some water and haven't really had a problem since. But I do try to avoid large puddles now too.... As mentioned, a drop in filter for your stock box it probably the best option.