Well to convert to T-tops, the roof structure needs to be changed completely. The way it is on all non-spyder 3S's is basically a rectangular frame with sheet metal as the roof, (that's why it's relatively easy to put in a sunroof, all you do is cut a hole in the sheet metal) Meaning, the top of the windshield is one side of your rectangle, the doors are the two others and the top edge of the hatch is the fourth. to give-'er t-tops, you need to chop out the structural members above the doors and put a nice strong one in the middle, making an "H"shape if you look at it from the side. hope that makes sense. But it looks like I didn't answer your question of how much it costs.... I seem to remember reading a thread a few months ago about this. searchy searchy....