There has been a lot of discussion about this on the list and you may want to do a search on the list archives.
Some say that they notice a drop in mid range power with the modification. I have not noticed such a problem with mine.
It seems to keep the cold idle a little lower. Not much of a problem much of the time, but a little bothersome in really cold weather. I find that it works fine for me if I drive about a block before turning on the rear defroster. On a cold morning with the heater on, the lights on, the radio on, and the rear window defroster on the engine may stall immediately after starting. Doing something to lower the alternator demand seems to help. Some remove the plug during the winter. Some have two plugs and use the one with a slightly larger hole in the winter, but most just leave the same plug in there year around.
Try it. You'll like it.
