Cerwin Vega Fan

I was at auto parts store and this guy had his truck running on air and I told him how I would like to have that setup in my car, but the kit would add to much weight. He claimed that since you removed the heavy stock suspension componets that the kits hardly add any weight to your car. The guy said at most you would see a 10-50 pound increase (50 is wayto much). Is this true? If so I might start thinking about bagging my car.