I know they work, i drove a Tundra on 33's with one and it was awesome. However, i think I would rather make my own turbo kit for a fronty/xterra...since no one makes one yet and Toyota has a nice turbo/offroad following for the Taco/4Runner.

The turbo is sized just right that there really isnt any lag...basically if you want to really know what lag is its the ability to feel the transition from stock hp to full boost. If your running a 1000 HP on a engine that was originally a 200hp I4 car, then yeah since there is a large turbo being spun, you will feel the transition of 800hp difference. However, if your using a well sized turbo on a 3.3L V6 with originally 190hp...maybe pushing 8psi, you will likely be around 320-330hp. So you will feel less of the transition of the 130hp difference. Plus since the spool will be faster due to the smaller sized compressor wheel you will feel less lag. Then there is the tunning aspect, if it tuned correctly you can experience a very very small amount of lag in the form of building power...not a sudden jump to peak HP.