I got a set of David Silver Spares no number pipes today. The price was close to Yamiya but shipping in the US was a lot lower $250 vs $18. I previously got a set from mach IV motors off ebay, which I suspected to be Yamiya's. The two sets appear the same, the mach IV pipes were packed in foam while the DSS were packed in newspaper and cardboard. The DSS have an oriental logo on the box and Yamiya instructions inside so I assume they are the same product. I always wondered if they were.
The DSS pipes arrived in perfect condition, the mach IV pipes had a few very small scratches all in places that can't be easily seen. Possible were seconds. I haven't tried to install them yet so I can't comment on fitment but if there are any issues I'll take pictures.