This is how my truck is ran. Everyone asks if its the 5.4 cuz it sounds righteous. The drone isnt bad at all on the highway. I can hear my tires over the muffler drone. Here's my setup:

2 Gibson High Flow Headers
stock pipe from headers to Super 44
3" pipe out
2 4x18 Tips

Sets car alarms off idling through the garage... and me likey like that

 

Well sorry to all of the Flowmaster haters. I have a 2007 KR and put a flowmaster classic 40 on it. Single inlet single outlet. Cut the factory muffler out, installed Flowmaster in same location, installed weld-on stainless tip. The tip wound up costing as much as the muffler but it sounds great and didn't cost a fortune. I like the factory location of the exhaust so I wanted to leave it. I paid an exhaust shop to do it all and it costed $180 out the door for everything.