Guys over there have tons of knowledge on modding the 8.1L. It is not as simple as "chipping". EFI Live is the most recommended path for upping the performance of the 8.1.
Believe it ir not, the 8.1L is choked really bad by the computer's torque management. Turning off the torque management will make you swear you added an extra engine under the hood. When you consider how well the 8.1L runs in stock form it is hard to believe it is constrained as bad as it is.
Also, regapping the plugs, and a 180° thermostat is a common upgrade as well. There is no issue with the computer going into closed loop while running the cooler stat, so all is good to go there.
There is an explaination on the dieselplace about why the cooler stat helps performance. Cooler is better.
I have a Nelson Performance custom tune in my truck, and it is awesome. I told them what mods that I did to my truck and they sent me the PCM(I think thats what it is called) and I sent the old one back. The truck is scary fast and pulls with the big dogs, even with 173,000 miles. My DW is driving it this week because her burb is in the shop, so I had to give her driving lessons so she did not smoke the tires at every stop light. If you want better drivability do not take all the TM out like I did, only go 80%. When I get my new 8.1 in my truck, which will be a long time yet, I am going to have them retune this tune to match the new motor.
I have a question for 8.1 owners. Have any of you chip'd out your big block?? If so, how have the results been. I've read horror stories about chip'd out trucks and read success stories also.
..........Most tuners\chips remove ALL Torque management that GM incorporated into the engine computer too protect the engine as well as the Allison trany ! Use a tuner knowing that you'll eventually have to rebuild the Ally , no free lunch for those that wish to play . , jf