Pretty much loud, there is alot of loud.....

 

it sounds like a lot pitched buzzing noise, while u can still hear the regular flow master mufflers.

 

See my first post in this thread. To check to see if that's it, check up over the axle where the exhaust is routed. If it's pretty close to something, it will rub making the noise you are describing.

 

i know the electrical noise its nothing to do with the exhaust....my car did it stock. it happens on newer chevys i think it has something to do with the sound system like my changer. and just some electrical thing. it does it in my car, my dads silverado, my bosses silverado, and our two suburbans lol. they are all 1999 +. so i think it is an electrical thing with chevy.