I have a 2014 mustang GT and I'm going to set up the exhaust soon. I am planning on an X piped with 40 series flowmasters out the rear. I know a set up like this will add a bit of horsepower...my question is how much HP will this add?
Well make sure you get an X with converters, you don't wanna lose the back pressure. Flowmasters will be ok, Im not a fan but they work. I would say 5-15HP maybe, and that IS a maybe. These new cars already flow pretty good.