compressor housing shoved over it. But here are pictures of my GMS 550BB turbos. Before putting the motor back in the last time I ordered some gt28r compressor housings but it seemed they were not even close to bolting on without extensive mods to the backplate, WG accuator bracket and accuator rods, it would out out weighed the cost of more powerfull turbos.The way it mounts to the back plate was totally different, so....... that was my failed attempt to make them like Z1 600BBs. But im happy with these, ill enjoy them for as long as they let me, they will be good at the auto-cross events.