A downloader (Superchips) will up the timing a little bit and allow you to change shift points within Superchip's set parameters. Its basically a fail safe if you do not know how to tune so you cant fuck anything up.
HP Tuners will allow you to change just about everything on your vehicle, and will net you more power if you know what you are doing, but it is very easy to fuck something up if you dont know what you are doing.
The TBSS's eat up 4 credits, but like everyone said, when you buy it you get 8 free credits. Normal F-Bodys and some Vettes only take 2 credits.
HP Tuners has a list of how many credits need to be used per vehicle. I think if you purchase 12 credits, you can do an unlimited amount of TBSS's per year, so basically 24 credits will allow you to tune however many 06 and 07 TBSS's you want
Your wrong on more than a few points.
HP Tuners only takes 2 credits for the TBSS, and 2 credits for the Corvette C6 LS2. HPT only lets you modify the PIDs the software has a function for and is limited to the trans controller and engine controller parameters. It will not let you look at or program the body computer, the ABS computer or anything else.
Superchips lets you change to three driving modes, performance, economy and towing. It lets you modify shift pressures for all gears and shift speeds for 1-2 and 2-3 shifts independantly. It lets you unlock speed limiters and change rev limiter settings.It lets you change tire size settings. It lets you log data for analysis on your PC. The superchips performance tune removes torque management as well as modifying stabilitrak thresholds (I haven't had stabilitrak kick in since the programming with Superchips). Superchips also has testing modes to time general times, 0-60 and 1/4 mile times.
Superchips will also analyze your data acquisitions and produce a custom tune for you if you ask.
With HPT you are pretty much on your own.
That being said, I have both, mostly because I bought HPT then Superchips did 2007 TBSS performance testing with my car and they gave me the programmer.
If your not into technical stuff, Superchips is great. It's also a source of dyno tuned programming that increases both performance and mileage. I have currently been running the superchips performance tune for about two weeks. My 0-60 logged with HPT scanner was 7.8 seconds before the superchips and 5.9 seconds after, my mileage has not gone below 15 MPG average since (which is remarkable as my AWD TBSS never got better than 11.3 average since it was new).
Superchips also reduces the IAT spark retard and increases the threshold temperatures, making heat soak less apparent on accelleration and mileage.
