I've relatively recently started working on doing my own tuning due to a lot of the local shops closing. I have a 2001 Silverado that is my current project. I started with hp tuners but today I started my use of the obdlink lx with pcm hammer to correct a Vin/OS mismatch on a P59 for a friend and swapped another P59 from a V6 OS to a V8 OS so I could use my unlimited GEN3 truck package for hp tuners. Thanks to everyone that has helped create the open source tools to make all this possible.