MMT is evil. Don't use it. Ever. Most of the major brands are Top Tier qualified now. I've always used 93 octane Shell (60,000+ miles, 2011 5.0 GT Premium), which was Top Tier qualified before the other majors except Chevron, and never had a problem with pinging even with the FRPP Pro-Cal tune.

If you can find it, some stations sell 100+ octane lead free gasoline. But it was $7/gallon at my local station. Unless someone can show me evidence that higher than 93 octane actually increases power, it's not worth it in a stock engine. Now if I had a supercharger...