I put a set of Tim's tubz on my ole ranch truck as she does a fair bit of towing and a few more mpg can't hurt. I am very pleased with the results. The truck has more power now and with a half turn of the fuel screw a lot more. It only smokes a little on initial spool up and sure makes the drivetrain growl if I get into it too much below 1500 rpm. I have to get a fan clutch back in my truck as the fan is always on and really sucks the hp. My recommendation is to get a set of tubz if you don't have one already. Now I have some TORQUE. Not quite as much as my '03 but enough for the NV4500 and Dana 70 I am sure.