Hi

I changed the rear shocks recently on my 03 g35 sedan. I'm don't remember what brand were they. But after the replacement the car seems lower than before from the back.

Is that normal? Or does it mean the shocks are not good enough to handle my car?

 

Shouldn't have made a difference. The shocks should only affect the rebound from the spring to keep it from bouncing. The spring it ultimately what affects the ride height.

To see if the shock is working well, give the corners a push and see how quickly it rebounds and settles. As you push it should firm up and become harder to push. If it's bouncy and becomes more bouncy with pushing on it them the shock is bad or not doing it's job.