Saw these the other day and it was so stupid simple that its just brilliant. Yes, you can buy jigs to finish out your 80% lower (here and here and here), but they are pricey. And seeing as you might only use it once, then why fork out the cash. These new stickers are only $3!
They get one bad review because the guy was sent two of the same side in the one that he bought, but for $3 who cares… just order another one.