any one do this does it help with either mpg or power??
i was reading on a hypermilling board a few weeks ago about it and ive been thinking about trying to do it
here is a site that explains it and the theory behind it...
im only talking about part 5
How To drill and index your spark plugs for better performance/economy. | eHow.com
Now that you have a very efficient set of plugs you need to install them correctly. Most professional mechanics don't bother to do this either, but you will be glad you did. Saving money at the parts store on high end plugs, and saving fuel at the same time is well worth the extra few minutes of effort. With a permanent marker or some kind of scoring tool (the tip of the 1/16" drill bit works well) mark the position where the outer electrode connects to the base of the plug on the side of the plug where you can see the mark from the top when installed in the head of the engine. When you put the plug in you want your mark to face away from the center of the combustion chamber. The rationale for this is that if the back of the electrode is facing into the combustion chamber your spark is directed toward the outer wall of he cylinder, and a lot of the spark is wasted. You want the spark directed into the middle of the combustion chamber where all the air/fuel mix is. Think about trying to start a fire with a match, but you can't get close enough to the fuel to light it. Put the spark closer to the fuel, and you burn it more completely. This is called indexing, and a good parts store will sell indexing washers for doing just this. Don't use a washer on every plug. first try one plug in the first hole and if it lines up fairly well on it's own your done, if it doesn't line up try it in another hole till it fits in line. You usually only have to use 1 or 2 washers on a V-8. Sometimes you will get all 4 to line up without a washer at all on a 4 cylinder. Note that the washers are all different thicknesses, and are marked in degrees of offset. So if you have one hole that is consistently 90 deg. off use a 90 deg. washer to line it up.