Originally Posted by MuellerJoseph
I like HushPower ProSeries Shorties for my 2007 GT 4.6. Check out HushPower.com; They gained about 15RWHP. But which ever you choose get a quality dyno tune to go with any mods. I got an average of 37.4 out of my car with the same mods I have just added a 93 Octane Dyno tune. It helps to tune. Got the hushpowers plus a throttle spacer a k&n filter only and 4.10's. Still not sure where my dyno tuner pulled the extra horsepower from because my car only made 240's RWHP with these mods. Then took same car to HPP Racing and tuned it they got me in the 280's?? As far as drone I can't say because these are the only axle backs I have run?
I you like HushPower you could get them at American Muscle but I pulled mine of Amazon for around half the retail price from AM. If you want a Sound Clip let me know?