Philips dvd-r 8x

yeah ive bought these disk for $10 a 25pk and ive tryed them with my lite-on dvd burner 1633s newest firmware but i can tell if its burning at 8x or 4x on my record now max i put it on max but it takes around 14 mins for a full dvd is this about the right turn around time on a full 8x disk begin burned?