Just changed out the plugs and wires this evening and I have a few questions. 1. Do the cylinder head covers over the plug wires provide a function in any way? (i accidentally put things back together without installing the rear one) 2. Do these look normal at 87,000 miles I think that they are Denso Platinums so probably not original but not OEM (not sure when they were last changed since we just got it in November).