It has a gtyr slip on, don't know if its been tuned for it, does it need to be? Also if I get a k&n filter will I need to get an efi controller? Is there a filter that doesn't require a controller?

You don't always need to adjust it with only a slip-on especially on efi. but to be safe so not to hurt. remove the spark plug and check the color after riding it for a short time white electrode too lean black too rich, and brown to golden brown = good mixture. you can also tell by the power. does it pop and crack when reved on or when the gas is let off means too rich. and loosing power when cracking the throttle is too lean.

x2 I would run a PCII or III controller and not only help with the way the quad physically runs but also to get optimum performance out of it! P.S I would also try posting this unde the Yamaha forum to get your best results!