I bought one of the Jet Modules for my 97 454 Suburban. It was easy to install and I have never had a problem with the Chip for 10 years I have owner the car.
Judging form this Jet makes reliable chips. Basically what most of these modules do is to alter input to the engine PCM from sensors etc and the main result is more ignition advance.
More advance generally = more power but you usually have to move up a grade in gas to mid grade or premium. Usually you get a slight increase in gas mileage as an offset. A lower temp thermostat is also a good idea. I read a dyno test of the Jet module on a Chevy and it netted about 17HP on a small block truck. I felt the difference in my big block and the engine had a slightly different sound at idle confirming that something was actually changed. I never did put a timing light on to measure the difference though.
Be forewarned Every engine is different, so I don't know how well this works with the Nitro. I have seen on test of a Jet chip on a 95 Impala SS that actually reduced power. I would like to hear from someone who found a dyno test of the chip on the Nitro.
When I get my 3.7L 6spd Nitro, I am inclined to get the chip.