So, over the past month or so I though I felt a slight hesitation on accelerating hard with the E53 but I put it down to being paranoid. Car ran without any issues otherwise.

A week ago I replaced my trans filter as it had been there for 40k with a lengthy pause 10k back when the engine was out for quite a while. Since the car was 10" raised I decided at that time to also swap my fuel filter as it probably had been in there for over 50k. Car was used for about 400 miles since this work was done.

This afternoon the car started fine but would not accelerate. I parked it and took another car to downtown DC. Got back and tried again with same result. Added about 15L of fuel, no improvement. Rather it got worse as it now cranks for a up to 5 seconds before the engine fires. Given that the filter is new, I presume my fuel pump has bitten the dust....

FCP offers a Bosch branded Pump/Sender unit for $198 which I feel tempted to buy. Anyone have experience with this unit? Given that this is 1/2 of the OEM pump and FCP's lifetime warranty, I think this is a reasonable alternative but I'd like to hear your thoughts?

__________________
2003 4.4i black ext./black int./black headliner (kid's runabout)
2014 535d X-drive, M package, silver/black interior

Sold but not forgotten:
2009 E70 35d, black ext./black int./black headliner (sold 2021)
2006 4.8iS Le Mans blue/cream int./black headliner, SOLD in 2012 sadly...

Other hardware:
2015 Cayenne S (wife's new DD and definitely wroooommmmm)
2016 Tundra 1794 edition crew cab, luxo hauler
2005 Tundra crew cab, weekend hauler. Sold after 150k very happy miles.