At least 3 zeds at the last Scottish meet were running Eibachs on M Sport suspension. No issues.
Several have fitted Eibachs on an ///M, again no issues.
If you buy cheap springs, with high spring rates, this may wear out shocks quicker and give a bouncy ride. However, Eibachs are quality springs which do not require upgraded shocks, and often improve the ride quality vs OEM.
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