HID's flickering or buzzing is a common problem with JK's. The CANBUS systems that runs the electrics doesn't play well with HID's. Apparently you'll need to put a capacitor into the harness for your HID's in order to even things out a wee bit.
I can't recall the details (didn't look all that close at them since I don't really want to go with HID's in my JK), but if you search through the electrical section on project jk forums, I'm sure you'll find a hockey sock full of info on how to put HID's in your JK for that riced-out look