I've heard this is a one time use deal.
if so does that mean after you load the tune it is useless? or can you still adjust for tire sizes etc.?

 

The originals are load them and forget about them. You can return it back to stock, but it's not good for any other vehicle than the one it was purchased for. I've heard rumors that they will be getting some options on the tuner for tire size and gear changes and such, but I don't know if they ever went through with it or if it was even more than just a rumor.

 

when i ordered mine....i had to tell them my tire size and gear ratio along with the vin#. so everything comes programmed into it...all u do is plug it up and hit YES. i also heard that you can buy the radix without the tuner(-300) but Magnacharger wont warranty anything