Since I got the car one of my complains is how poor the headlights are, I read here in the forum that several people have switched to h9, all you have to do is to cut a piece of plastic and trim the edge. You can find instructions in youtube.Why not use the proper bulb?
As for adjustments, IDK, sorry
Sorry, you are right. H11 bulb .. crystal vision 100% brighter.The h9 I installed required modifications, nothing hard; overall I'm satisfied with the results.
Not sure about the Crystal vision for h11 which is what the GT would require, maybe next time if I have to replace them again.