I put about 3-4k on them. the Previous owner put 20k. I have not done anything to them besides install them on my car. The rears care a bit noisy on bumps but they do have Group N top mounts. Also if I remember correctly his WRX was a 2003.. so it would possibly fit on a 02-03 w/02-03 strut mounts.
All and all this is a soild coilover and I wouldnt be selling it if I was keeping the car.