Guys -
I just did this upgrade last week and this is my recommendation.
STOP what you are doing right now and run to get the Progressive springs installed right away. Holy smokes does the bike perform like a sports bike now. It is very well planted and can take curves at a higher entry speed. Bike feels solid and planted.
One word of caution - it will no longer be a cushy ride. You will feel a bit of harshness up front but that is expected on a stronger spring setup.
Did not do the rear spring - I feel that on the middle setting it is strong enough for me. 5'10" and 190lbs. The springs did lower the bike about 1".