I recently came up with a figure of at least $17,000 invested in my ’97 Ford F-350, as it sits right now. I know some have spent less, but others have also spent much much more. Another question: What is your favorite modification? As for the ’97 I would have to say either the John Wood Automotive street performance E4OD transmission, the traction bars, or the Adrenaline high-pressure oil pump.