[StraightOuttaCanadaEh]

In all seriousness, if it bothers the OP, he should casually mention it to the owner, something like "hey so I saw you guys revving it and bouncing it off the limiter, you probably shouldn't do that". If the owner replies "shit man, sorry, you're right, we're just car guys and get excited, won't happen again" then it's all good. If it's some snarky reply, or any indication that the owner is failing to understand why this is important to the OP, proceed with the negative google review and don't go there. The business lost will be ample punishment I think.