hi there
As an official supplier for over 7 of the top suspension manufacturers I should be able to answer that one.
35mm on original dampers will be fine. Your car will feel alot nicer to drive and you will notice quite a difference on round a bouts etc...
If you were to lower the car more than 40mm then we recommend that you would change to dampers to match so as not to lose performance.
Ideally you could do with changing the dampers as well, but as i say its not a necessity with the drop you are looking at.
For a quote on springs email me direct:
GSleigh@GSMotorsport.com and we can sort you out with some great prices and quality products