Nec 3500 speed

Hi i have a friend that have the same burner as me bu if but in a 4x dvd so can i burn it in 8x but he can burn it in 12x why is that so ?
Sorry my english bad.
my nec is sett as master and my pioneer is slave
And i have my disks are on a controllercard

Maybe the media (DVD+R/-R) and/or the firmware he’s using
allows it.