Any reason you want 7" lights? Consensus is they don't put out more light than the 4" really...
If you don't already have a bar, I'd look into a good LED light bar instead. Much lower energy consumption, and super bright. Much 'cleaner' looking than a massive row of 5 - 7" lights on top!
You'd probably need an alternator to run thos HID's. The LED's will work with stock system no problem.
Just my two cents! Hope you find what you're looking for!