the wider the tip the louder the exhaust...i had a 4" tip on a car and after 2 weeks cut if off at the muffler and installed a 2.5" tip and the car sounds much quieter at all rpm...sounds more aggressive than buzzy too
the reason is the wider the tip the bigger the echo the louder the sound...depending on the size of the muffler's interal passage it does no good for power (only looks and sound)...for ~$60 bring it to a muffler shop and have it cut off and a smaller tip welded on (stainless steel requires a stainless steel tip)