I'm not sure bout it coz thats what i experienced everytime after installing new muffler the sound was very loud then after driving it and going to track the sound slightly quiter. Then after all fibre gone the sound louder but not so nice like before...
ya better do dyno run...but i think you'll find only minor change or no change at all coz it's just the muffler
ya better do dyno run...but i think you'll find only minor change or no change at all coz it's just the muffler