John- I have wanted to know the same info that Racer Oz asked. I guess we got the idea from looking at some of the pros cars that have been posted on this site. We never seen any discussion of what and why they are used. I am a yok guy and saw Tosolini's carpet car was running some batts and we were having some dump issues at a huge track that we run on in Mod sedan, so just trying to get the skinny....lol
Thanks for the info!
Jeff