I have joined the tweecer group. I guess the big thing I am looking at it for, is that I will be doing a lot of stuff on my car over the next few months and the dyno tuning will get expensive not to mention being able to get in to see the tuner. There is a local group that has a dyno but they don't do dyno tuning on Mustangs. At least not yet anyways. I can rent their dyno and tune myself for alot cheaper than having someone else tune my car. I am still not sure if tuning myself is something I want to get into but from I read the tweecer software also comes with full datalogging capabilities.