I have a 2012 Mitsubishi Challenger diesel that I use to tow a 2.2- tonne caravan and I have been offered a TDC Power Box performance chip. Apparently, it works by modifying the electronic signals that control fuel pressure produced by the pump in order to optimize engine performance. It's designed to increase fuel pressure at the pump to maintain rail pressure in the mid to upper operating ranges, increasing power and torque. Would this be a worthwhile modification, or is it too much of a risk? Would it have an effect on comprehensive insurance or vehicle warranty?
It won't affect your comprehensive insurance, but it would affect your new-car warranty. It's a modification to the car, so anything that is affected by that modification wouldn't be covered by the warranty. I wouldn't fit it myself, I don't believe it would have much affect, other than probably increase the fuel consumption.