For one, I would estimate that the additional shock will weigh at least 3lbs. Then you have the aluminum adaptor, spacers and bolts, washers, nuts add at least another pound for that then you’re up to 4 to 4.5 lbs. On top of it all they attach the shock to the inner finder which is a very weak support with no boxing just stamp sheet metal spot welded together.
This set up will work but you want see anything like that on a front running racing car.
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Unsprung weight is a measurement of the weight of everything outboard of the wishbones or suspension links, plus 1/2 of the weight of the wishbones or links and spring/shock. It has a great effect on handling. The diagram below demonstrates why unsprung weight is so important:
The more weight outboard of the car, the more force bumps exert on the suspension (and ultimately the chassis). This force must be dealt with using springs, dampers and anti-roll bars (described below), and the more force, the more difficult it is to keep the tire planted on the road. This is especially true of lighter weight cars. In the example above, if the car weighs 1000 lbs, a 2G bump would result in a vertical force of 10% of the car's weight. This will at the very least reduce the grip of the car, because the weight of the car is what keeps the tire planted, and pushing a car up into the air with that much force will inevitably reduce the weight on the tire, and hence grip.