My old 94 Camaro didn't have a rear defroster so you could see the line. The guy that did my 01 TA which of course had a rear defroster followed a curved defrost line and damn he did a sick job. You COULD NOT tell it was two pieces.

And yeah FYI no one can do a rear window of a 4th gen F-body in one piece. I suggest Eclipse Window Tinting on Military Hwy behind Autostar near Freedom Ford.