I have an 87 E30. Fought fuel starvation issues in the early, small fuel tank. Solved with the VW Sirocco fuel accumulator. Installation takes about an hour. I like being able to run with a full, half or mostly empty tank and don’t have the engine cut out in a hard corner. I did not mess with installing the larger tank because the pump electrical plugs and sending unit plugs are different.
Problem is the accumulators are No Longer Available from Ireland or Bimmer Parts. They are no longer available in the US because VW does not import them into the US any longer.
I have been able to get a source in Germany. I have 2 accumulators here in the US. $120 each plus shipping and includes the fuel line routing instructions. I am headed to Germany in September and can buy more.
I don’t know how many folks out there have the same problem. Am I the last one? You can PM me with questions or an order at firstname.lastname@example.org.