Like Michvalk said...I wouldn't molest a clean set of stock pipes...check out ebay and find a set of used pipes if you want to go modifying them.
With that said...I modified my pipes with glass packs and truck stacks. Definitely not the as quiet as the stock pipes...but not obnoxiously loud either. Check out the video clip for the sound...
http://vid412.photobucket.com/albums/pp202/JoeValkIS/IMG_1452_zpsc5d4cdae.mp4I used the instructions on ShopTalk (link on top of this page), adjusted them a little to suit my desires and had a muffler shop make mine. They cut the mufflers off a few inches from the collectors and welded in a reducer. They then welded a half-coupling to a 24" glass pack (2" inlet/outlet). Since I wanted the end of the glass packs near the end of the truck stacks, I inserted a nipple between the reducer and the glass packs. I think I got the sound I was looking for...nice mellow, not too loud, but louder than stock sound.
Joe