I've been using my DIY rcm for a few years and have had a few opportunities to compare it with a VPI 16.5. Mine wins hands down if what you're looking for is the absolute loudest vacuum in a rcm. (I've got to build a better cabinet, maybe in the next room or a closet with a really long hose.) My wife giggles at this because I absolutely hate the sound of a vacuum running in the house. Central vac in our current house has solved that issue, but she never misses a chance to point out to me how loud my rcm is. But, it's my vinyl!
Hummmmmmmm? Wife? Loricraft? Wife? Lori. . . Oh hell, I'm sure gonna' miss her!