I just got a set of Cusco Zero 1 for my DC2. thinking to get new springs with higher spring rate, Front 12k/ Rear 10k. my question is what spring length should I get? 8" length or 9" length??

 

First question you should ask is if those Dampers will be able to handle those spring rates.?.
As far as spring length goes, I believe 8" is the usual.

Are the coilovers separate preload and height adjustment? Did you get a good deal on them?

 

Currently they are front 9k/ and Rear 6K. 5 way adjustable and height adjustable. I got them for a good price. Do you know if cusco Zero1 can handle 12K/8K???

 

Maybe you should contact Cusco?
http://cusco.co.jp/en/about_us/contact/

 

most coilovers you can go -/+ 2kg from the standard rates they give you.

But for sure call Cusco to confirm, ask for Stephen he can get you taken care of!