$800 for a set of Z springs???!!!! Thats a bloody rip!
FYI, I've got full Z suspension in both my sedans and they lower the car all round by approx 1".
First set I was lucky, got the set for $110, 2nd set bought for $300, this is for the full Z suspension both with approx 10,000kms.
definately recommend you get the matching Z spring with shocks.