I run and rec XFI in my own cars. If you want a Wideband correcting system with a lot of logging potential. XFI does a great job supplying updates to firmware for free also. There are a lot of people that can help with XFI in this community. Most of the fast turbo Regals have XFI. I use a powerlogger to view data obtained while running the non correcting stock ecu as well as stock ECU with Wideband. I clamp an oxygen sensor in the exhaust if no bung is available and log pulls. I do it all the time and can dial in fueling and timing very quickly. Because of the limitations of the stock stock timing tables I use the logged mph data to have new chips burned timing variations based on mph instead of rpm. I am able to increase reliability and make more power at the same time with these devices. It all depends on what you are looking to do. If you aren't familiar with what's required for timing and fuel for different loads and combos then I wouldn't attempt to use any programs without a lot of help. These things are controlling your engine and simple oversights can be very costly. Interpreting the data is as important as collecting it. If you want to have an emissions compliant LS combo then HP tuners is a great idea. Id find a shop that is familiar with it and have them dial in the car. I still strongly rec XFI if you are going to make 100+hp per hole.
I'm using HP tuner, as it was in the car when I bought it, its fine for my use, but with out buying the programmer, you are left to using a dyno shop ( good idea) to tune it,
I've used XFI, and now HP tuner, both work good, with more latitude in XFI
my stock ECM controls the 4L80E, which is programmable with HP tuner. (a big plus!)
