I would use what TEIN reccomends regarding ride height. They do a lot of testing to figure out these numbers and while it may seem strange, the uneven ride heights will give you the better balance. That is the way our cars come from the factory as well. Whiteline in another thread said the same thing.
The first thing that most people try to do with coilovers when they get them is to make them even front to back and while it looks better, it's not optimal.
Here is the thread I was talking about