How much gain with lower gears?

Your won't know till you run a back to back test, but odds are, you won't see much difference going from 3:23 to 3:73 with your 408.... I have ran a 3:55 gear, swapped in a 5:13 and the car ran the EXACTLY same et
That's what I was wondering. Maybe I'll just leave them in and see what I get. I was going to freshen up the center next week and thought while I had it apart it would be easy to swap gears if there were gains to be made. I guess it's a more trial and error thing than an exact science.