I put one on my E body. Don't expect a BIG difference.
I called Firm Feel and talked to Dick before I bought it, he said don't expect a BIG difference. He said all of the individual improvements I make will add up to a BIG improvement in the steering and handling of the car.
I also installed a FF steering box, tubular upper control arms, idler arm roller bearing kit and Bilstein shocks. This DID make a big improvement. The car handles close to a modern car now.
Very pleased..