I forgot the gearing ratio numbers and had to look it up, I did this mod a while back, the stock 4.27 gearing came in the 92 lexus sc400 automatic tranny, the sc300 dif. gearing on a manual transmittion is 4.08.   I apologize for the error and I was quick to write that 3.08, my mind was somewhere else, your comments are in line and I was totaly in error.  However this thread is accurate, and I am not backwards you are with all due respect.  I had to go back and see what I did.   Now apply the speed theory as stated above.  If I could attach the lexus dif. ratio sheet I have in front of me I would.  Yes the top speed is reduced, the speedo is off 10 miles per hour, and the shifts are a bit quicker from start and so are the 0-60 times, the rpms ride a little higher at freeway speeds and the gas mileage is not as good.  That is how I can best describe the setup.   Disregard my prevoius post as complete garbage.  Now double check this info. and you will see that it is correct.   I am aware this is a very intelegent forum, I will be very careful in stating future facts.   I hope you are satisfied with this post.