We developed this M16x1.5 restrictor fitting for the BMW E46 M3 and some GM LS V8 Power Steering Pumps. These two pumps are not restricted internally and need the fluid restricted and slowed down. If the pump over-pressurizes the rack, the fluid will overheat before it's even in heavy use. Your steering will feel soft and flimsy which is bad for drifting or road racing. Eventually it will overheat and blow hoses off no matter how high end the fitting or connection.
This fitting adapter is 6AN Male to 16x1.5 Male threads with a 3/32 restriction hole design that dams the fluid up so it's not over cooking your setup. It is machined from 6061 aluminum then anodized Chase Bays Signature Black. It includes a crush washer. Do not over tighten these adapters, they barely need to be torqued down to make a sea. It's better to be too loose than too tight and break a fitting in your pump.