NO MODIFICATION NEEDED, this plugs right into the valve cover and uses two o-rings that are provided for perfect tight fitment
This works with any motor that has the obd1 m50 or s50 valve cover... works with non vanos m50 as well

 Flapper Delete Fitting for N54

WILL NOT WORK WITH RALLYROAD FUEL RAIL THAT HAS A RETURN FUEL SYSTEM

 AS SHOWN IN PIC (NOT THE PURPLE FITTINGS)

also known as the flapper delete fitting for the n54 powered vehicles