Currently I have 700-250-550 Ground controls in my Civic. I want to go to a 700lb rates. But they don't offer it in a 7" 2.5id spring. They do offer it in a 8" 2.5id spring. Would that be good to add an inch and just lower the spring perch buy an inch?

 

Yup.

 

or a 6" spring would be fine. depending on your desired ride height. you really will just subtract or add an inch to the perch position it is at with the same spring rate.

 

Check block heights too...when selecting higher rates within a given length, the block height becomes shorter due to thicker coils. You simply need to make sure the new heavier rate springs have enough travel for your application.

Eibach's website has a great spring chart. Pick a 7" spring for goofs and giggles and see what happens to the block height when you change the rate - up or down.

good luck