Measured 4+ inches with me sitting in the stock passenger seat. I plan on pushing it up a little more and in a little more to reduce the "intrusion". I mocked it up to test and getting in and out of the car my legs do not go anywhere near it. I am "only" 5'10"... Josh checked on his convertible, he would probably have 2" less space.
I will do some more fitment testing. The dash frame I have sitting in the car now is a "damaged" spare, so I am not afraid to cut it up more than it is. The lower dash pads are beat up extras also.
I have a local upholstery shop that I am going to work with that can make my lower pad and recover the upper. He does Ferraris, Lamborghinis, Maseratis and lots of custom work. We already talked about the pads and he is on board.