I have 2 center sections for my Dart dragcar.One has 4.10's and the other has 4.86's in it.My car has a best of 11.48 in the 1/4 and 7.27 in the 1/8 with the 4.10's with the mild small block .With the 4.86's its crossing the line in the 1/8 at 6200 rpm and with the 4.10's its crossing at 4900 in the 1/8.It runs a better 60' with the 4.86's (1.57-1.58) ,but costs me a bit in the lights .With the 4.10's it will 60' around 1.60 or 1.61 .Believe it or not it runs exactly the same ET with either gear in it in the 1/8,but its easier to get it to leave and proly easier on parts with the 4.86's in the 1/8 anyway.I gain a bit off the line but give it back on the other end.BTW the 4.86's are useless for the 1/4 in my application thats why im hanging on the 4.10's for the 1/4 races .Confused yet ???..