Hi Justin
Upgrades for the 2010 4G are
1. The 100 tooth is now a 80 tooth = 4:1 ratio
2. The free wheel is now in the 80 tooth not the 11 tooth = larger one way bearing/ free wheel
3. The 11 tooth drive sprocket is is now a 10 tooth non free wheel = stronger free wheel
4. The trans side cover should be smaller
And all 2009 4Gs can be upgraded to match the 2010 4Gs
Terry
Upgrades for the 2010 4G are
1. The 100 tooth is now a 80 tooth = 4:1 ratio
2. The free wheel is now in the 80 tooth not the 11 tooth = larger one way bearing/ free wheel
3. The 11 tooth drive sprocket is is now a 10 tooth non free wheel = stronger free wheel
4. The trans side cover should be smaller
And all 2009 4Gs can be upgraded to match the 2010 4Gs
Terry