for example a car is tuned with efilive can it be adjusted with hp tuners and then altered with ls1 edit? or once its tuned thats the software that must be used?

 

I've had EFI Live and HPT hooked up to the same car. The problems may occur when you start introducing custom operating systems. If you stick with the factory OS, then it doesn't matter if you use HPT or EFI Live. Some software may have different tables than others (ie LS1edit doesn't have all of the tables EFI and HPT have). As long as you read the current tune in the car with the software you're using to make changes with at the time, you should be good to go.