They are all VGT (Variable-Geometry-Turbo) but the 03/early-04 ones have less vanes in them making them much much louder lol. Almost ear piercing loud with an open filter intake and a straight pipe haha

 

I forgot to mention my work truck has a K&N intake if that makes any difference. I may remove the cats at some other point but removing the muffler was just quick and easy at our shop.

 

Get that K&N crap filter off your truck before it destroys the turbo! You don't need to do any intake work on the 6.0 PowerStrokes until you're past the 500hp threshold.

 

x2

The factory Donaldson filter/intake flows plenty for stock to close to stock applications. And it filters out and holds more contaminants than any other which saves your turbo from getting shredded.

Only intake setup that has anything relatively close to the filtering capability and capacity of the Donaldson is S&B.