remap=chipped,mapped etc etc. need to do some clever tuning anyway.
problem with adaptor plates is the clearance downwards.
a turbo option is the gt2256 from a x3 3.0D,vnt turbo.almost plug and pray.sufficient to 270 bhp
just make sure youre getting the vacuum operated one.
tuning threads about the m51 engine is almost non-excistent, but some swedes and some finns have some info in their native language.