def 12". it looks cleaner imo cuz the light isnt broken up.
How exactly did you make yours plug and play?well, you need to cut and connect the power and ground wires for the ccfl rods transformer and your cars oem wiring for the license plate light, most people do it that way. i just made mine plug and play sorta, so i could change it back if i needed to.
That was something else I was wondering, whether it was better to use 2 x 4", 1 x 9", or 1 x 12"?

How exactly did you make yours plug and play?
That was something else I was wondering, whether it was better to use 2 x 4", 1 x 9", or 1 x 12"?
Where do you mount the one in the trunk? Does it always stay on when the parking lights are on?i got two 12" ones in the trunkhahaha