Thats a tough one. My guess would be a li ning or kason grip. I think your best performing, lowest priced grips would be the RKEP ones from ebay. Just look at the response in that thread... I'm using the li ning ones, don't remember the model#'s. They're ok, not spectacular. I don't like the one with with the wave tread pattern because it doesn't last as long as the regular rubber one.
There is a photo showing CY grip in a match with a typical Yonex tape. It would be very strange if he used Kason or Lining grip with Yonex tape. Therefore, the possibility of CY using YY supergrap is quite high...