i just tapped the holes, stuck m8 threaded plugs in there, and flap wheeled the boxes down to make it easier to pull the cover out for valve adjustments. the pair system doesnt do any harm, or good. but it does get in the way during services.
The main reason I did it is to get rid of the backfire / popping on deceleration and that is exactly what it did and did it well. GONE! The other not as important to me benefits are: Easier valve cover removal and get rid of the now un-needed piping/hoses .