From a quick google, it appears the R888 is in another league as suspected, but the Yokohama is probably better for every day use as well.
BTW if you changed to a 19" rim, you'd need series 35 tyres. i can't remember the best tyre sizes, but it may have been 265/35 and 235/35 to match up OEM rolling radius.
IMO, if you only track it and/or drive in the dry, get the R888's, otherwise the Yokohama's are about as good as you'll get
Ekona will be along shortly with his expertise