And some people cant notice if they have a dead cylinder, bad brakes or a slipping transmission.

Same goes for the balance shaft eliminators. Some dont notice a difference, others do.

I remember doing a test drive and mentioning to the owner that he had no rear brakes. He was sure I was kidding, because to him his car seemed just fine. After he got them fixed he still didnt notice the improvement.

87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...