Originally Posted by 2010SSRSM6
Should be close to 465-470 rwhp on a Mustang dyno. Sounds like you either have bad gas or a bad dyno.
I doubt that Carmax actually put premium fuel in so you are likely dealing with crap gas and will have to do the fuse pull after a few tanks of good gas to reset the fuel trims.
Thanks for your reply. I have a few questions.
What fuse needs to be pulled? How does pulling a fuse reset for fuel? will that reset the computer as well? In other words if I tune the car will it need to be retuned after the fuse?