If you use the coilovers, then you can use any spring rate you want and still adjust the height the way you want - independent of the spring rate.
With such a small sidewall, you are not getting any additional flex or "softness" to cushion the ride. It's like using higher rate springs, so you may want to go with a lower rate spring - along the lines of the Stock Audi Sport Suspension. A good reseller (who you buy the coilovers from) can tell you what rate that would be.
VB
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