how many rpm's will i drop going from 3.91 to 3.55????????????????

duster360 said
Been thinking about pulling the 3.91 gears and going to 3.55. About how much of an rpm drop would i see at cruise speed.

here is a nice little calculator to check with all different gear and tire sizes..
http://www.bigblockdart.com/forum/speedtire.php

going from a 3.91 to a 3.55 will make a little difference but not a huge one.. i did it in my dart a few years ago and it took the edge off some but the car still wasn't great on the highway. all depends what your looking to do with the car.