They check everything. I got a yellow a couple of weeks ago for my blow off valve (which happens to be the standard one.. But when I told the young hero cop that it is the standard bov, he replied "bullshit, skylines don't come standard with a bov" to which he was confronted with a few choice phrases, but let's not get into that.. -.- )
So I can't help with the other half of the question, but I can say that the pit inspector told me they don't care what the cop wrote on the slip as they don't know what they're talking about half the time so everything is checked.