just finished flowmaster install

[BlackGT97]

I just finished my flowmaster am th c/b install. How much increase in horsepower would it give for my car being that everything else is still stock? I mean this is the first thing i have done. I also know that modifying my induction would make the flowmasters more effective, but how much more?

 

[40th GT]

The cat-back exhaust exhaust doesn't increase much hp (if at all) in our 4.6L Mustangs. However, I heard you can gain up to 10hp by changing the midpipe.