Lowering springs play a huge role in the following (ride quality, chassis stability, ride height and they support most of your vehicle's weight). Without isolators, you have metal on metal contact, where noise, and vibration is easily transmitted...period. This vibration will and does affect your ride quality. Ford did not install isolators on their Cobra R vehicles...why? Because it's a race car where noise, and vibration isn't a concern. On their production cars, they install isolators to help isolate Noise Vibration and Harness (NVH). Can't say I'm familiar with how people use an inner tube, or whatever to isolate NVH but if there doing something then NVH must be real. Do it the right way, buy the right part for your car, and don't take short cuts that don't work properly. If you're looking for a certain ride height do it the right way, buy lowering springs that give you the ride height you're looking for or get coilovers where your ride height is adjustable.