change in 1/4 mile ET?

Of course I installed LT's and 4:10s blah blah blah... just like everyone else the 4:10s made the biggest difference in ET but the headers ehh not so much. So my question is how much of a difference will a tuner tuned by the right guy make in my ET. Keeping in mind I'm lucky to run a 13.9 lately and has never been tuned.