The stock diff has a tendancy to break with stock power, so with FI it is definitely recommended. You WILL need it and most likey a new clutch depending on mileage, so if you buy that car plan on spending at least $1000-$1500 in parts not including labor. Also, the upgraded jackshaft was a service offered by a member on this site and not Vortech. If it does not have this upgrade it is HIGHLY likely to fail in a short amount of time. This is why if you browse the FI forum you will notice that a huge majority of the FI CSVTs use the ADC turbo kit.
