im not even sure if its call that but something of that nature. what do they do and are they needed when installing new springs? thanks

 

They are used to either raised the car a tad after lowering, and/or reduce spring and body travel on the drag strips. They come in both circular and cube form and rest inbetween the coils of your springs. What they really do is raise the height or your car about .25" or so and increase the spring-rate of your suspension. They are not necessary and I think only two or three guys on the board have used them.

 

Is this something I should consider when I'm towing? The rear end doesn't sag too much when I have a trailer on, but it is noticeable. Are they easy to install and remove?