To get more torque, you want longer injection times. More fuel (larger quantity per combustion cycle) will raise both horsepower and torque. If you just want torque, you are looking at Steinbauer (will use more fuel, guaranteed), but injection timing is also important. Take care that the injection period doesn't go too long in the cycle, because diesel burns slow and at higher RPM there may not be enough time in the downstroke for all of the fuel to combust. A perfect example of a low-revving powerhouse:
[YT]https://www.youtube.com/watch?v=uf7-ONreQwI[/YT]
I'm not sure if Unichip adjusts injection duration but it does adjust timing.
ChipMyDiesel shortens the injection duration and raises the rail pressure so that the fuel input is the same as without a chip, but ALL of the fuel is delivered earlier in the stroke, so the effect is a larger push on the piston followed by nothing - this equates to more apparent horsepower and less torque. I have a personal issue with fuel rail pressure raises anyway, given that they're already running 1700BAR (1800 for the V9X).
I am not sure about RedDirtDiesel.
I feel that the front runner is Unichip, followed (a fair way back) by Steinbauer. 3rd place is a LONG way behind and was ChipIt, but I am not even sure if they're manufacturing any more.
