For anything but the simplest of mods, a custom dyno tune is gonna be better, though you'll hear from plenty of people on here that BAMA makes great tunes for a very wide variety of setups.
If you've got nothing on your car yet performance-wise (which I think is the case, based on your other posts), I suggest something like this:
JLT Mustang CAI & SF3 Tuner (05-09 GT) at AmericanMuscle.com - Free Shipping!
That way you get a decent start. get yourself a CAI, and tuner, AND you're set up for any other mods in the future with free tunes for life. You can also get it without the CAI, but it's very common to start there.
The short of it seems to be that you will be fine with mail order tunes until you go Forced Induction or a serious engine build.
I'm sure other people will have more details for the question.
If you've got nothing on your car yet performance-wise (which I think is the case, based on your other posts), I suggest something like this:
JLT Mustang CAI & SF3 Tuner (05-09 GT) at AmericanMuscle.com - Free Shipping!
That way you get a decent start. get yourself a CAI, and tuner, AND you're set up for any other mods in the future with free tunes for life. You can also get it without the CAI, but it's very common to start there.
The short of it seems to be that you will be fine with mail order tunes until you go Forced Induction or a serious engine build.
I'm sure other people will have more details for the question.