kx100 shock spring too short?

[terminatr]

Hi.
I got a Factory Connection shock spring for my '11 KX 100.
I need new spring because I'm 150 pounds.
This spring is 1" shorter than the stocker. Is it normal that the spring is so much shorter?

The new spring instruction says max preload is 10 mm. It says do not exceed that because
it will bind the spring.
But I had to set the preload to 15 mm, in order to get the proper racing sag of 85 mm.
So is this 5 mm of extra preload going to bind the spring? And if it binds the spring what bad happens?