[techweenie]

The washer tank weighs a few ounces. The tank above it is a chamber for catching fuel vapor. It weighs even less. Not worth the bother of removing. If you want to save weight, don't put any washer fluid in.

Also, you're right that this isn't the end you want to remove weight from. If it were me, I'd take the entire back bumper, shocks and shock reinforcement metal off the car first and just use a one piece fiberglass rear bumper. You can do the same in the front. You will feel the difference.