It's all about the ratio. Stock bikes have to compromise the link ratio for a passenger, something like this is designed for single rider only situations. The ratio is much closer to 1:1 and will transform a Gen4 from a wheelie monster to a corner carver. You will most likely need to change rear spring rate to use this correctly. On a Gen5 it's not a massive difference but it will still be better than stock. Edge grip is improved, wheelie is controlled via suspension much better and rear end traction confidence will go up.