TIS2000 is the software that links your Tech 2 to to the PCM for flashing. There a couple ways to legitimize it. One being with an internal software crack file on the laptop used to write the PCM. The other is a USB Dongle that has the cracked file in it. It can all be downloaded from the net for free. There are limitations on autos above 2008 or so. Then once you hit 2013 IIRC GM went to a whole different interface making the Tech 2 obsolete and unusable. If you screw up a PCM, no worries. Grab a used one thats compatible and start over. They arent $5k at a salvage yard. Many times they can be had for less than $50. There are some that are cross compatible and just need your original VIN and file assigned and you are back in business. Best bet when you start is to look across the net for known compatible PCMs for your application. Many times odd ball autos that nobody really lines up at the salvage yard for and those can be had for $10-20 on ebay all day long. The guys running an LS1 in their GM Trucks/Suvs commonly start off with a corvette file. Deleting stuff that isnt wanted or needed. Of course tuning is a whole different ball game, one which I have much to learn. No more playing around with the battery leads to get a K chassis to relearn a new TPS sensor or debug the rear hvac module. The tech 2 will take care of it. Once I nab some Helm manuals for our chassis....then I can decode many common electronic/electrical problems in our chassis.. I didnt start playing with electronics at the age of 12 to never use it. I was raised around it, went to college for it, Your federal tax dollars paid for me to get more training while in the service. been working in electronics for decades. When I was 26 my daily job was repairing the F/A-18C Hornet. 12 of them were in my squadron.