How fast have you gone with stock headers?

[Shaggy]

Okay the first answer is i have seen low 10's but those were stock headers mounted upside down with twin turbos on them. In the intrest of giving you the answer that you are looking for though I have built several mustangs that ran high 12's all day long NA with the "stock" motor. What was changed on them was subframe connectors/pulleys/K&N/silencer removed/Gears 4.10's/slicks/minor weight reduction/mild porting of the head mainly grinding out the thermactor bump/timing/offroad h and not caring whether or not your T-5 lives. my opinion is yes the factory ones are little and pinched in places but they are not really the bottle neck they are made out to be.