Supposedly with the side pipes completely open and free flowing mufflers you can pick up about 5 HP. More if you're running boost.Boss949 said:Update:
Not sure why I thought there was better performance with Silver and not Red Key? I drove it last night hard with the Red Key and there is noticeable difference with both Silver and Red Key.
Not sure about HP claims by Roush, but I can feel a little performance.
My wife met up with me and followed me back to the house; she could tell a huge difference in the sound, which is what we wanted.
The drone is bothering me, driving and shifting around it anyway.
Side pipes sound different also.
So far, I'm extremely pleased.