Rarely
I rarely do soup them up but I've occasionally done it. The most recent one was my Lux Legacy upright. I found it original motor (VM3) annoying and underpowered for it's power draw. So i replaced the motor with the motor a modern Numatic uses. The CFM at the bag chamber increased by nearly 17, and it's not as annoying sounding.
[ATTACH=full]125430[/ATTACH]
[ATTACH=full]125431[/ATTACH]
[ATTACH=full]125432[/ATTACH]
[ATTACH=full]125433[/ATTACH]
[ATTACH=full]125434[/ATTACH]
[ATTACH=full]125435[/ATTACH]