My bosch pump has not got this bit

[mikey b]

Its for the load dependant timing. Makes no odds tbh, the are both exactly the same performance, but one with the blank off causes slightly noisier cruising speeds because it maintains rpm/advance curve where as the one with the pipe backs off the advance depending on how far your foot is mashed.

Ah that's cool was just wondering we just had both bonnets open and thort what the hell is that bit lol