I also have an auto with 3.31's on a 27 inch tall tire. I am installing 4.10's next week....going to the track again with no other changes...so if you can wait, I can tell you rpm difference (which you could figure out mathmaticaly--which is about 600 rpm higher). For me this means 2100 rpm at 70mph to 2700 rpm at 70mph. I can also tell you exact difference in 1/8 and 1/4 mile et when I run at the track with the 4.10's
There have been many other posts on this subject, but basically if you have an average size tire (26 or 27" tall) and you are N/A, go with the 4.10's. HOWEVER, if you plan on going with a supercharger, many people have suggested 3.73's.