Speeds depend on the media, best results with most media is 4x-6x, I mosty used rated speed (except with 8x PrimeOn which is not good media)
Best media is Panasonic, but hard to get and expensive
My 2nd recommendation is CMC MAG BA5, to find in Verbatim 6x-media.
Original Verbatim media is also hard to find
Pioneer is IMHO a better burner for most media than LiteOn