all the info i could find was the b4 is slightly firmer than the b6. I figured with the extra weight of the diesel up front the e300 might benefit. I'm not a fan of the body roll. Only the b8s are listed on the bilstien sight for lowering springs so i figured id just get a sporty ride. Its not bad just a little to stiff, probably put 150 miles and still stiff. if i get the B4s I'll update if they are the same length as the b6s before i send those back. The ride height looks more correct with the b6s than waterever was on it.