What do you want to use them for?
Why does the size of the light depend on the height of the lift?
Im running PIAA SMR 520's with a 3" lift, soon to be 5", and i love them. Although i will probably be putting HID kits into them if theres room.
The problem with any roof lights is the reflection off the bonnet, back into the cabin, causing glare and reducing visibility. I still have this problem to tackle. The way i used to do it with my offroaders was to paint the bonnet matt black, not really an option on a nice nav! The other option is to sit the lights further back on the roof, so the beam angle doesnt hit the bonnet, but again not an option if you are set on having them above the windscreen like i was. So the next solution is to make little glare guards to sit under the light, like this;
This is my next job.
As Carts says, the new LED light bars are very good, i've got a pair of small ones to fit as reversing lights and am planning on putting a 33" 180w one in the bumper mouth, plus sticking one of them on your roof would be a lot easier to make a glare guard for.
This is how X-mods over on club frontier mounted his;
Rich