Horsepower gain from muffler?

i have a 2001 dodge durango 4x4 4.7l v8 i was wondeirng if i get a flowmaster super 40 muffler how much horse power would i get just form that? im planning to change my headers later but for now if i just change my stock muffler to a flowmaster super 40 how much hp will i gain like around 9?


thanks
Horsepower gain from muffler?
Not sure how much HP you will gain, but there is a chance that the flowmasters will allow the exhaust to flow more freely, giving the engine more "room to breath" but if the engine is tuned to run on some backpressure from the exhaust, it may effect how the engine runs.
Horsepower gain from muffler?
Depending on the flow capacity and restrictions of your current muffler, you should gain aroung 5 HP. If you make other modifications then you would have more flow and subsequently need a less restrictive muffler. The muffler on the car currently is probably about up to par with flow. Most mufflers are grossly overrated when it comes to HP gains. Replacing your entire exhaust system would probably only give you around 20 HP more. You probably will not be able to notice the HP gains from a new muffler. The only thing you'll notice is a *nicer* (depends on how you like it sound and a louder sound. Hope this helps.
Reply:you will get some but little... you wont feel it much at all but it will sound better ...and maybe nine sure
Reply:Not alot, not enough to feel definitely, you should do the full exhaust instead of just the muffler....