The conventional six speed isn't equal to a five speed with a longer sixth - it's like the five speed with an additional gear in the middle.
The real way to get a taller sixth gear is to pick up the Legacy six speed transaxle that is more or less a five speed with an extra gear stuffed in it.
To the original question: Of two engines that I pulled the plugs from, both had the same malady - the plug closest to the driver was different than the other five. There might be a little freshness to be found there?
