I broke down an bought the Denso Iridium spark plugs last week at $12 a plug from Auto Zone.

I got the IK20 for the first plug that fires and the IK16 (reccommend plug for 1999,C280) for the 2nd plug in the cylinder head.

12 plug total.

The plugs have very fine wire tips and are well made.

They work real well in the motor. Very smooth idle and better pickup on the gas. No noticable increase in power in the upper part of rpm band, but I think they have improved midrange power to some degree.

The plugs I removed were Champion Plats and were 1 year old.

Overall the price is high, but they do smooth out the motor and make it pull harder in the middle.

Jeff