What was the reason for changing from a B to a D ?
The B is VERY weak and fails (mine did). There is a rubber diaphragm on the B version that splits after a while and you lose boost pressure. The D version uses a piston and is much stronger.
I think there needs to be some clarity on the part numbers here.
06F 145 710 B had a black diaphragm > this was replaced by
06F 145 710 C which had an orange diaphragm > and these were all ultimately replaced by
06F 145 710 G (dunno what difference is). These were all designed for the
original 2.0 TFSI engine (in the Mk5 GTI, with the rubber timing belt). These are all now NLA (no longer available) - and are replaced by the current . . . . .
06H 145 710 D. Note the crucial bit, the
H in the first three digits - this (a piston design rather than a diaphragm) was originally designed for the newer chain driven 2.0 TSI/TFSI as used in the Mk6 GTI (and others) - but has been decreed by VWAG as backwards compatible with earlier engines including our belt-driven donkeys.
This latter 06H variant is now all you can get - even if you were to specifically ask your stealer for say the 06F 145 710 G, you would not be supplied with this G version. If someone was particularly keen on a G version, then the only legit way of getting one would be from either an independent, or places like GSF or ECP.
EDIT: for cr@p spelling & clarity