Tape or screws---I used the tape. I love looking in the rear view, even during the day, and seeing people squint because it is so bright and obnoxious. It is really a surprise to those behind you when the running lights are off and you tap the brake or flip on the turn signal because it is kind of hidden until the bar lights up.
Just replaced my stock headlight bulbs with the PIAA extreme white bulbs and they made a huge difference.
In case you can't already tell, I really like those behind me to have no reason to say they didn't see me and I really like to see everything in front of me as best I can. Gonna replace the stock fog bulbs with the same PIAA bulbs as soon as I can find them.