Quoted from CrazyLevi:Real knockers are overrated.
If nobody had ever told me games like monster bash or spider-man didn’t have real knockers I’d probably have never known.
I grew up in the Arcade Era. Hearing the 'knock' meant your quarters get kept in your pocket for the next play. For me, it's important, and I am saddened to hear a screech(virtual knock). I don't mind buying a Knocker kit, they are a relatively cheap mod for newer Stern. I'm glad that Stern has soooo many awards (High Score, modes, loop champ, etc) that you can enable to get a free game 'knock'
IIRC, WMS and CGC MB both have real knockers