i have the chance to buy a JLT CAI and SCT tuner that is "unlocked" for a fair price. i have a 2010 mustang gt all stock with mufflers. eventually down the road i will be installing LT headers and off road x pipe. can i get a tune written and emailed to me from some the the popular tuners like brenspeed or bama? or would i have to get a tuner from them? also, when buying a used tuner what is there to look out for?