I've had both a ZR2 and a Vortech V1. One thing you notice is the Zr2 is a lot easier to spin so it spins up quickly and doesn't suffer from belt slippage. I think they recommend you change the oil every 15k miles in a zr2 and you have to remove the charger to do it. The Zr2 definitely ran cooler than the Vortech -you can barely touch the vortech when it's warmed up without burning yourself! Overall a good reliable unit. Things to watch out for on the Zr2 would be wear (dishing) of the toothed drive pulleys and oil leaks.