305 HP 2003-2004 are great motors. No emissions nonsense, boatloads of power, and decent economy. IMO, these are the last of the motors that actually sound like a Cummins. Put mine next to an 06,07 (esp. 07. 5), ya can't even tell the newer one is running. Not as "embarrassingly" loud as a 98. 5-02, but definitely closer to a 12 valve as far as idle noise is concerned.