the major difference is the spring rates. With cheaper brands like OBX/Drop Zone the spring rates are incredibly high for a street car. I believe 500-600F/500R. Those will kill off any normal shocks w/in months. GC offers lower spring rates that may be more streetable. Some pple have claimed there's a difference in quality, but these are problems that plague all "sleeved" coilovers such as freezing perches