Go to the Force Induction forum and do a search.

The preference is subjective but the numbers will show that Vortech produces more out the box.

 

I've talked to a few people in socal about supercharging and both have its ups and downs. For example, Vortech has more potential of pushing bigger numbers but voids the warranty (unless your warranty has expired obviously) or if you're under warranty and you get the Comptech, it doesn't void it.