Front Runner and how they affect ET and Speed

Like some info on front runner size and how it affects ET MPH and 60ft. At the track today and my brothers challenger ran 11.34 at 121.7MPH 1.67 60ft. I noticed he was only running a 24" front runner and 28" slick on rear. How different would these stats be with a 28" front runner. Thought there might be a calc for this but cant find one.