If I am buying Works spring, is it needed to go with the Whiteline kit? recomended or a must?
How much lowering will start to need such kit? Since the Works is lowering about 1inch.

 

I couldn't tell you in your particular case, but let me stick my neck out and say for street driven car you don't need the whiteline kit. in other words unless you do lapping sessions or race/autocross you will never get to that need.

just had the whiteline put on my car, couldn't feel any difference in daily driving. My car is at least an inch lowered, via coilovers.
I do expect to get an improvement when I'm 8 or 9/10s on a road course.

 

My main urpose of lowering the car is for track performance, I do quite a few track days a year. Otherwise the stock suspension is good enough for street

 

Great.

I'm going by what people have said, that they are necessary. I'm thinking you could go with a bit less camber with them, but didn't have the nads to go less. We will see.