I'm pretty sure submissions about YC funded companies are juiced.
So no juice needed. Just regular voting.
I'm not complaining coz I'd do the same if I was in YC. HN is just like TechCrunch in that YC startups 'unfairly' get more exposure than non-YC ones. Building unfair advantages is essential to startup success.
It's not YC doing anything, just us the audience clicking on the arrows.