So, I just bought some Jegs Cat Deletes and should get them next week. I have had older SN Mustangs in the past in which the Cat deletes consisted of an off road H or X pipe. With these newer Mustangs I am assuming that I only need the cat deletes right? Also, the ones I got were 3" in diameter. This is the stock size I hope? I also am thinking that the Check Engine light will come on too. Will that go away with a tune? Should I also replace the stock cats every time I go into the dealership for warranty reasons? Sorry for the newbish questions but these new stangs are very new to me.