Depends. I watch them take my old one out but he used a seperste cutting tool. But my window was not original. I have a chap doing my glass both supply and install.
I'm going for after market glass that looks like orignal including the slight blue tint through the glass, the black across the bottom and blue glare strip across the top, $375 installed.
There is a chap in sydney that can supply original screens but he wanted $550 just for the glass. I got my door windows from him at $660 and they were in Pilkington box's. So go figure. Mind you they look fine to me. Just like the originals but bloody expensive. If you want his details let me know and I'll get it when I'm at my factory. Having said that the guy who is doing my windows is really, really good and can supply the glass but not original from the states.
I have extra clips to hold the top mold of the windscreen. I order in extras from the states when I got mine as I was sure someone would need them. When it comes time to put yours in give me a call and if you need them, you can have them at whatever they cost me, if your interested.
PS Stay away from Obrians and the chain type shops etc.