[123Britt]

Well, I would review for possible ease of installation.
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I replaced my downpipe independent of all the other operations you listed so I really don't think in matters where in the process that falls.
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However, I did remove the Coolant tank and the cooler below it which gave me great access to the turbo inlet . I replaced the thermostat and water pump which did provide excellent access to the DV (I did not replace). Wrench Lab videos on Youtube do provide an excellent how-to on the 235i cars. I really had no plans on replacing the turbo inlet until I found the hard plastic pieces brittle and broken.
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With the proper access it is really a straight forward job to R&R parts on the N55.