I got a new exhaust system on my rig just last week, and I've never been happier...
It's the stock manifolds, and 2-1/4" alumized tubing (nothing fancy or flashy) into a simple 2-into-1 cylinder shaped turbo muffler with a single 2-1/4" out dumping right behind the passenger rear wheel. Most of the system is up above the frame rails. It's quiet, at all speeds. I used to daily drive my rig, a 'cool' sounding exhaust sure wore me slick after 100 miles or more per day for a few years. It's got an ever so slight rumble at idle, and a little bit of growl at speed, but you can't hear it with the windows rolled up and radio playing. ;D
I sold off my headers and duals for this...