I have the same Fuji 4x blanks. I tried your speedhack and was able to burn at 8x with no problem. Thanks for the tip and the great hack.
Thanks for the reply. I had considered buying 8x Riteks. Good to know that they work.
Thanks for pointing me to a thread I read before I posted. Some people actually do use the search function.
I wanted to know what actually works, not which brands "should support 8x." Also, by posting my question, code65536's response prompted me to use his hack, which I hadn't considered before.