The whole trick to running a loud muffler is to exit it some place outside the body lines. If the sounds can echo to the sheet metal from dumping it on the ground under the truck you will get a whole lot of noise passed back to the passenger area. Pay the extra for a tailpipe. I love my Magnaflow. Spintechs are getting popular, too.
But they're pretty much retarded loud regardless of where they exit. I've had mine in three places now. lol
1969 Chevy RCLB C10 350/TH400 SOLD
2007 Chevy RCSB 4.8 4x4 LS SOLD
2008 Chevy RCSB 5.3 4x4 LT SOLD
2010 Chevy CCSB 6.2 4x4 LT SOLD
2005 GMC CCLB DRW 6.6 Duramax 4x4 191,000 and counting
2013 FORD CCSB F350 6.7 Powerstroke 4x4