The 6 speed transmission technology was indented for improving fuel economy while continuing to give reasonable low end acceleration.
My 2010 XLT Screw 4.6 3V with 3.55:1 gears would out run from a dead stop my '04 STX regular cab or '07 XLT Screw both with 4.6 engines with 4 speed transmissions.
Don't forget to consider increase of hp. I don't know about the 5.4 but the newer 4.6 engines have more hp and torque than the '04-'08.
Last edited by shortride; 09-15-2011 at 10:25 AM.