To be honest diffuculty level is pretty high for doing this, its a total pain in the butt! But if you are serious about weight loss this is a good way to shed some pounds. On a serious note, you are removing the crash bars from your door with this mod, the crash bars are there to protect you in the event of an accident. Do not do this mod on a daily driven car, this mod is suggested for track use only and a full 6+ point roll bar/cage is highly recommended. On that note, on to how its done.
First thing to do is remove the door panel...although if you're serious about weight loss I'm sure you already have! Next undo the bolts/screws that hold the door handle/lock. You won't want to cut the two little bars that control these. Here's a pic of what your door will look like without the panel on it.
Grab yourself some sort of tool to cut the metal portion around the door out. Make sure if you use a sawz-all that you use a short 4 inch blade or you will be denting the outside of your door...you'll see more on this later.
Now remove the rubber trim (just enough to get to the spot welds on the rear portion of the door) You will need to drill through these spot welds. A spot weld removal tool would work great, but a drill bit also works.
Be careful when you start to feel the bit going all the way through, fortunately my car is in need of some exterior body work anyways, but this dent shows you what happens when you pop through the metal and hit the outer metal of the door.
Drill out all the spot welds...The top one in this photo did not need to be drilled, all the rest were holding the crash bar in.
At this point I decided to remove the door, you do not need to do this although it does make this job easier, I also removed the glass, there are two bolts holding the glass to the power slider, remove those along with the entire power window assembly (there are two bolts on top and two on bottom). Once you have all the bolts out you can remove the power window assembly, careful the glass may start to slide down. You can remove the glass by pulling it up, pushing it out away from the door and pulling it up and out...carefully.
Whether or not you remove the door, you will need to remove the little piece I circled in red above in order to get to all the spot welds on this side of the door, again be careful drilling them out.
Now you need to cut through the glue that holds the crash bar to the outside metal, I used a hacksaw blade, others have used long razor blades, piano wire, and whatever else they can find. Once you've cut through all the glue, you'll need to cut through the bar in order to remove it. You cannot cut through the middle of the bar, it has a plate welded in the middle for more rigidity, you can feel under the bar until you are away from the plate on either side, this is where you will cut it. There is no easy way to cut through the bar without hurting the outside metal on the door, the best way I've heard of is using a dremel tool with a cutting wheel and being extremely careful. I used several different methods including a sawz-all and a drill, it was a long, slow, painful process but I managed to cut through it without doing too much damage, I suggest find a different route however.
Once you've cut through it you should be able to break it loose from whats left holding it in from the spot welds and pull the crash bar out.
Now you have your finished product.
How you figure out how to hold the glass up is up to you, I'm going to try to find some lexan and just rivet the lexan in to hold it.
I weighed everything I removed from the door and it totalled 20 lbs. This is a total weight savings of 40 lbs. if you do both sides. The door now weighs 50 lbs w/factory glass, gutted and without mirrors.