I have the same car as the TS, and stock gearing would only allow 149 MPH at about 4200 rpm. I switched to 3.73's and didn't like them, too much shifting for a car with a V8. (this is a non PI motor). I switched to 3.55's and am fairly happy with them but it handicaps me at the track. I used to be able to hold 4th till around 126 mph on the front straight at Pacific Raceway, now I am at the redline at 120, necessitating a shift that costs a couple of mph that you have to then make up. I make it to 123 max now before having to stuff the brakes at turn 2, and this has now necessitated another downshift. That is a lot of footwork. It pulls a little harder out of the turns but the sacrafice up top is hardly worth it to me.

 

If you're hitting 140 in 4th gear than you must have stock gears. That's what I hit at the top of 4th before I put in the 373's.
No I top out in 4th at around 120-125.
Since being blown I've hit 150 in 5th turning 4500 rpm, and she was still pulling when I got off it.