for those wanting to modify the exhaust without significantly increasing the volume of the sound... ... my system is now on, and i love it. nice deep sound--lot's of turbo sound at the tailpipe. used a 4" Goerlch's straight thru truck muffler, a 4" downpipe, and a 4" tailpipe. a Megs stainless steel "Slick Tip" finished it off. 
