I never based a tune's value upon 1/4 mile times. Too many variables.
If anything after a complete build on a prior vehicle I had, my times were most disappointing as I had to practice to apply the new found power.
For me it was always proven on the dyno. Those are the numbers that matter to me.
In addition to be better transmission shifting, AFM delete, etc.
When I used to race regularly, we did not have access to a dyno. So we measured our performance gains from the modififcations based on our ET and MPH and in my opinion is a more accurate and real world way to measure them. One has to be disciplined though when testing this way, keeping the car at the same weight, same fuel, adjusting for outside air temperature, tires, etc. The most important aspect is to only make ONE CHANGE AT A TIME and get at least three passes down the track to see what, if anything, the modification did.
Dyno stands can and do get out of calibration and one can take the same car to three different dynos and get varying results.
Take your race weight, the trap speed and plug it into a math formula and you will know your actual rear wheel horsepower.
The dyno is a great tool to use for programming and certainly costs less in time and money for testing.