I have an Audi A6 3.0TDI from 2010 with very low mileage (65000 miles, 105000km) and no apparent engine problems.
I got a note from service about suspicious sound coming from the high-pressure fuel pump. They (local Audi dealership) gave me a price for OEM replacement around 1700 EUR (bit over $2000) for the parts only. At the same time, I can see Bosch aftermarket HPFPs on various web stores for third of that price, like here
A friend who owns a car repair shop says that this sounds too good to be true. And besides, I should add 2-stroke engine oil into fuel and see if the noise disappears. Which I have been reluctant to try so far.
However, makes me wonder what's the deal with these aftermarket HPFS? Is the Audi original really that much better to justify the triple price? Bosch sounds as serious enough manufacturer, so how are they so much cheaper?