Is that part of the pulley or just a dust cover?
good question because i'm not sure. I'm assuming you are asking if that center parts with the crack is a cover, right?

I'll have to take a look at mine. I don't remember having that cover at all.
I have an '01 GT and mine looks exactly the same. The pulley is not cracked - the hub for the pulley is. And it is not harmful for the engine. It's the hub that thepulley mounts onto on the water pump. I also have the steeda UDP's , and if anything, the pulley is actually keeping the pump hub from further cracking by keeping it compressed.