Hey guys, I have a completely stock Mustang GT I just bought, anybody know how much horsepower I would gain if I bought Flowmaster 40's with 3.5 inch tips? Please get back to me. Thanks!
That hunk of junk? Yeah, well I've made a few special modifications to that yellow 99 Gt, it makes the Kessel run in 12 parsecs and eats turbo japs and poops chevy's
No question the quickest and best way to pick up at least 20+ (conservative) Rear Wheel Horsepower. The best initial bang for the buck modification you can make. But exhaust and Mustangs are just like Harleys, you've got to change the mufflers. The 4.6 does sound schweeeet running through RPMs and some better flowing mufflers.
My advice is to buy axle backs strictly based on the sound. A lot of exhaust companies lie about or decieve you into thinking that you will gain a lot of horse power when in fact you will gain very little if any. Pick the one that sounds best to you!
My advice is to buy axle backs strictly based on the sound. A lot of exhaust companies lie about or decieve you into thinking that you will gain a lot of horse power when in fact you will gain very little if any. Pick the one that sounds best to you!
Excellent point.
I would also recommend getting mufflers that use some type of packing as well (glass, stainless wool, whatever) like a turbo-style or derivatives there of. They make excellent sound, flow just as well, and don't tend to have the harmonic droning like the chambered (Flowmaster) style.
I have the Ford Racing 49-state axle back and love it. The only remotely droning noise is when throttling down in gear (stick) it makes a very sweet sound at 2200-2400 RPMs. Nothing like the 2 and 3 chambered Flowmasters I have run on 5.0's which would drown out everything else resonating through the unibody at about the same RPMs.
Exhaust Horsepower gains for 2007 Mustang GT 
