Throw the plastic washer/ring away, it's wank and not what you need

Get some standard EFI washers to go above the o-ring, should be able to pick them up at any tuners
Interpro sent me some for mine FOC

Drill the pintle cap out to 3mm or leave it off, the choice is yours

Fitting greys for the first time is a twat cos the fitting kit is wank , once you've done it once tho