e39 530d inlet manifold

Don't put the swirl flaps in as in time they may come lose and be eaten by the engine, then it's one way a trip to the scrappy.

I would by a BMW bit for something like the inlet manifold.  OEM injectors should be fine provided they are bought from a reliable source, don't buy a second hand injector.

Why are you needing a new manifold?  Is it cracked or has a broken off bit of turbo vane damaged it?

What is the condition of the turbo like?  Might be worth checking if you are poking about the inlet manifold.  Make sure there is no wear in its bearings.

apparently  it does have swirl flaps

which suggests that at some point the inlet manifold was replaced

according to the mechanic 9who is an approved bmw approved servicing garage ,there are 2 flaps missing and he fears that the others may get loose and cause damage

the question ?

1) remove the existing flaps   what is the consequence

2) buy replacement flaps as suggested earlier

3) buy a replacement manifold 

i have located a  highly reputable dealer in germany  who can send me one for 160 euro total

a new inlet manifold from bmw would cost me £460 for the unit alone

this does not include fitting

i have purchased a new fuel injector

i presume i would wait to do both jobs at the same time