Those K&N's are severely overrated. They may improve your response the slightest bit, but the plug up with dust in no time. My friend had the exact same mods on his warrior (before I added the majority of mine) and I still pulled ahead with the pro design foam w/outerwear. He had the pro design K&N with outerwear on the contrary. The main difference was seen in the dust when his filter was plugged in two days to the point where the machine wouldn't even run right. After 4 days of riding I was still running strong with a very slight rich condition, which was nearly unnoticeable and almost no power loss. My other friend on his z had the same thing happen to him, but it wasn't as bad as the other guy.