Who cares.

I have had a set of kmacs and they were not bad, a friend has also had a set which broke in half. I also have a mate on here who is using coilover sleeves and has not had a single problem either.

It all depends on how low you want the car and the price you want to pay, usually the more you pay, the better the ride quality.

Just to put it into perspective, you can get a complete set of kmac springs at any height for $200. Kings are about double that and they only offer specific heights. The coilover sleeves are anywhere from $300 to $500.