The Road Magnet Mercedes 190 springs were designed to be used with up to 20 wheels. They fit 1986.5 to 1991 models and lower the ride height 1.5 with plenty of room for passengers and a full trunk!
Z's are notorious for negative camber when lowered... I haven't had ANY issues with replacement of stock suspension parts. Yes, I've had my springs on for almost 2 years now, and I had them on my RX8 for 3 years and my wife has had them on her RX8 for 2 years now too... ZERO issues...