cis injector interchange and flow rates

To me, most if not all cis injectors look the same but have different part numbers. Are the flow rates the only difference? Possibly length? The reason I'm asking is, I need four injectors and I want to find used ones at the salvage yard. At the nearest place I found two GL-5 quantums and a Mercedes V8 with cis, but no MK1's. What would be the biggest difference between these. I have a '83 Rabbit GTI. Would there be a possibly of getting higher rate injectors from a differnt engine that would work with a 1.8 with performance mods? Thanks!

As I understand things, there's detail differences but all mechanical Bosch injectors have the same pertinant characteristics - opening pressure and flowrate, etc. The merc ones are brass, I think, whereas others are steel? They differ in fittings but these screw onto the injector itself.

Mechanical injection is different to electronic, in that you don't use "high flow" injectors to allow more fuel to flow. Its about reducing or controlling the control pressure and lever/air flap position, ie with mods done on the WUR and basic mixture setting. The "map" of fuel flow vs airflow is set by the shape of the cone, and is slightly alterable with control pressure changes, eg using a 16V WUR which can lean out at low throttle and richen at high throttle.