The PO of my Miata had a set of the Aerospeed coilovers. They were crap. The sleeves were taller than the shock bodies. They were a good 1/2" taller than the rear shocks. That ate strait out of the suspension travel for the car. Made the ride super harsh because they bottomed out regularly.
I could have cut some more metal off the top, but they just weren't worth it. It was too much easier to go with an FM setup.