Go with MagnaCharger. When I was researching them for my Silverado truck a few years back, I definitely liked what I read.

MagnaChargers come with a 4 year warranty against engine damage. However, the price for this reliability is that their superchargers don't put out the highest boost levels out of all the superchargers in the market.
MagnaChargers CAN run on 87 octane.
And, in Truckin' Magazine a few years back, MagnaCharger was the ones making the TRD Superchargers. I don't know if that is still an accurate statement though, as its been 3 years.