A bit of a mongrel job getting the front valve cover off with that double prong thingy hanging so low, that holds the pair valve. I had to bent it forward to be able to lift the cover enuff to slip it out. The inlet valves were 7 & 8 and exh both 9 - not as loose as the rear set.
Better to drop off the whole PAIR valve and related hoses. Benefit to environment from the PAIR is close to zero, especially when there is a catalytic converter installed on the bike. Engine itself does not need the PAIR (neither catalytic converter, frankly speaking). Next time it will be easier to do valve adjustments and bike gets cleaner inners too.
To close the PAIR issue correctly I suggest to use some cover set like this:
https://www.ebay.com/itm/254621096348
The GL1800 set will fit DN too, been there, done that.
Only thing you may miss later is the popping noise while engine breaking (if one may miss such noises...).
PAIR parts to be removed:
PAIR removed, new covers installed: