I don't scalp my yard, and might be completely wrong here, but I thought this was something that is done only to bermuda/zoysia in late Winter or early Spring.
If you do it now, I have a hunch that you'll regret it.
I leave my grass longer in the winter and usually see it green up before my neighbors. I take off the top dead grass and I have an instant green lawn after my first mowing.
IF I scalp my yard I do it in the spring when the grass has come out of dormancy. This way it fills in right away and I don't get as many weeds.