I know I have read a few things on here about this, but now I can't find anything on this subject to save my butt. I have a feeling my RPM's are higher than they should be after going from 3.21 to a 3.73 ring and pinion. Seems like I remember they should be around 2300 at 70. Im hitting 2500 at 70 and about 2650 at 75. I know your RPM's increase about 300 after a change like that but that seems higher than it should be. Right or wrong? Keep in mind, other than the ring and pinion, new axles, and new bearings through out the rear end, everything is stock that I know of. No obvious changes to the cars original setup that I can tell by looking at it. I still haven't had my speedo re-calibrated yet after the change, so I am basing my speed off the GPS. I have tested the GPS in other vehicles and it is right on. So there you go. Thats all I know, so let me know if I am wrong or not please.