What do you feel you are lacking with the 4.30?
Yes you will notice a difference. 4.30's felt like a bump up from the 4.10's. 4.56 brought it into a different game. Everything got quicker to do and revs up faster.
You will need a slick or some type of bias ply tire to race. I have tried drag radials (all brands) and they either hit or you blow the tires off. I am also launching at 6500 to 7 grand. I use Drag radials for daily drivers
Do you care about high revs, gas mileage, shifting twice to get across an intersection without reving up to 4500 rpm in 1st!
I have had 3.55, 4.10's , 4.30's and currently for the last 6 or 7 years 4.56's. take what I say as a grain of salt as other people have had the same or different experiences then me. I have had the car since new and started modding it about a month into ownership. Most of my testing of gears or rear end/ tire stories are on this site.
Good luck and if I would do it again I probably would have left it at 4.30's cause I could drive to the track with my Hoosier or MT drag radials, lower the psi to about 12 and pull of consistent 1.68 60 foot times and then put air back in and drive home with the AC on if needed!
Now I haul a jack, wrenches, air gun, 4 bias ply tires and whatever else I feel I need to change them up. I'm 54 and getting sick of changing tires at the track!
Good luck man.