My 2004.5 D/A CC just turned 12,000 mile... When the truck was new it would only run 93 MPH @ 3250 RPM's.This past weekend It ran 98 MPH @ 2700 RPM
I started using an additive about 1,000 miles ago.My queston is, is it the additive or the breaking in that caused this jump in power. If it were not for the top end limiter there is no telling how fast it would go.
ps everything is stock..

Do you have the same tires as stock?

Every thing is stock......No reflash nothing .... Getiin 18 mpg...

Thats weird. When the motor breaks in it will use lees fuel because the parts move better inside. The rpm vrs speed thing are prolly torque converter lock differences subject to the Allison learning process.