Picked up the wife a 07 gmc loaded out lbz all stock it's an lbz. Has 175,000 , miles her birthday is April 16th hoping I can keep it hid that long. She won't need to much power so what all should I have done to it. I'm def. doing efi live and I don't want to start a war here but who should I go with for the best mpg considering I'm sure she will take it on vacation an so forth. Thanks in advance guys