Can anyone enlighten me as to why some manufacturers' motors are so very quiet (Monogram/Revell ) while others' are quite noisy (Fly)? And then there is Scalextric whose motors are both quiet (NASCAR, Porsche GT1, TVR) and noisy (MINI). And Carerra motors make a wholly different sound all together. I prefer the quiet motors - they just give a sense of quality - as opposed to a loud whiney sound. Just wondering.