Hey, I recently installed a k&n cold air intake, but now there is a rattling noise when I accelerate, the noise seems to be coming from behind my dash. Has anybody else experienced this problem?

 

you are probably getting droning from the CAI, which is causing something behind the dash to vibrate. as for what that is it could be any number of things.
my Roush created so much droning I finally took it back off after a month or so. I am waiting til I can afford my Roush exhaust. once I get that I may put it back on and see if I can stand the droning or not.