I just replaced the spark plugs on my 92 SC400 and the misfiring stopped (mostly). There's still an issue with the delivery and I need to replace the wire set soon. When I put the plugs in I tightened them 1/2 turn after finger tight. However, there was some very confusing terminology, very foreign to me, on the back of the packaging for the spark plugs indicating how much to tighten them. I couldn't identify my car on the provided chart because I didn't understand the categories. It looked like a series of abbreviations to me. It runs fine now, definitely an improvement in performance, but I'm still in the dark about the tightening guidelines. Does anyone have an opinion about my experience or possibly some advice?