I`m running about 2800rpm @ 65 with 15" tires on the back and 3.55 gears, manual tranny.
Remember too, you did not change the tranny speedo gear, so more then likely you were driving faster then the 65 indicated on the speedo.(or you use to drive slower then 65 when the speedo said 65) Without changeing the speedo gear it will show the same speed and RPMs you were running at before as the change you made was after the speedo gear, in order for the speedometer to be acurate you need to put the right speedo gear in the tranny too.
Here is a gear ratio calculator, if you messure your tire size you can see what speed you should be running at what rpm.
Differential Gear Ratio Calculator
To verrify your gear ratio you could jack up the car and spin the wheels over one revolution and count the # of times the drive shaft turns, it should be 3 and about a quarter turns for every time the tires turn over once.
