well, congrats on owning your dream car. I also couldn't be happier with my Benz. Anyway, about the plug wires. The reason for the metal casing around the plug boot is just a form of insulation. The reason for the little tops of the plugs unscrewed is because thats how the boot fits onto the plug. If that wasn't removed the plug wouldn't stay attached to the wire. If you were wondering about just leaving the little thing on top of the plugs and getting a cheaper set of wires, don't. Take a look at the rotor. Its the same way. As far as i know there aren't any plug wires out there that have the two differnt type of connections at the same time. I believe this is why plug wires for MB are so spendy. I'd spend the money and do it right. Its the safest way to go. Good luck.......