uni-chip seems to be the only chip i have heard of that can adjust the spill vale and slightly adjust the timing of the injection via the slide gate (i thinks what its called)
The rest of the chips just open the spill valve for an extended period of time, add more diesel.
I paid $150 or something like that for a no limits chip, and it dead set looks exactly the same as the chipit chip that's like $1000. The case, the connectors, the size, the colour, everything about it is the same. All chipit has is a relay added to the harness so you can use an external trigger to shut the power off. It also has the chipit sticker on top.
Chip express seems to be pretty popular for the 3l models on here. And i think they plug into the injector pump harness, where as i had to solder mine into the harness
As scotty spud said, i'd def put an egt on at the same time. Once you start pumping the fuel in the temps will rise when your under it, even with the best intercooler set up it'll rise. I have a water to air set up on mine and the temps get as high when i'm under it as when the cooler wasn't on it.