One of my dads good friends that just got layed off from GM a couple of months ago just put a new 02 sensor on the passenger side of my car cause my check engine light was on and that was the problem. anyways he loves mustangs and use to own a couple when he was younger and did a ton of stuff to them performance wise. i know that sounds weird since he worked for GM but his dad worked for Ford his whole life and he grew up around ford's so thats why...but when i went to pick up my car from him today he told me that it sounds like it has an aftermarket performance camshaft in it cause he said when its idleing it has a nice lope sound to it...how could i find out for sure if it has an aftermarket cam in it? that would be sweet if it did cause i was considering that a while ago but dont have to if it already has one...