The more of these things I read the more I am glad I tore my engine down when I did. I am also glad I am going with a 66 tooth ring gear and matching pinion for my starter. Much stronger.
Just because the ring gear has fewer teeth (66), does not mean it is a stronger setup. Yes the teeth are larger on a 9-tooth pinion gear/66-tooth ring gear combination, but the 10-tooth pinion gear/102-tooth ring gear combination that came stock on your 2004 SEEG provides more gear reduction and higher torque multiplication of the starter's output. Having less gear reduction puts more stress on the starter clutch and the reduction gears inside the starter housing, and they become the weak point.
Tried the 9/66 combination on a built 103. It destroyed a 1.4kw starter, a 1.6kw starter, two 2.0kw starters (all aftermarket), and shucked teeth off a 9-tooth pinion gear and a 66-tooth ring gear all in about one month. Went back to the stock starter motor and 10-tooth pinion gear/102-tooth ring gear, and haven't had a problem in three years.
I hope this saves you some grief.
If you are still set on changing your starter gears, Rivera-Primo offers a 10-tooth pinion gear/84-tooth ring gear combination that would not reduce the gear reduction as much as the 9/66 combination.
http://www.riveraengineering.com