According to http://www.f-body.org/gears/, with 3.73s gears and a 6100rpm shift in 3rd gear I should have a top speed of 125mph.

Why is it my car stops at 120? It feels like it tops out. Is that just the converter slipping on the nitrous?

I only gained 6mph on the topend from a 100 shot.

 

Sounds about right figure on converter slip and variance on tire sizes . You might get a little more if you locked the converter at the top but i doubt the whole 5 mph

 

I would expect you to be looking at about 3-5% slip with
that converter. Which might account for the error, but a
slipping converter will still accelerate you some (not "hit a
wall"); more like a rubber band pulling less and less as MPH
catches up with RPM.

 

Well..not sure if this math is right...but.... 125mph (according to the calculator) x 4% slip = 5....so that would be my 120mph top speed..


Maybe I'll just add...MO POWAH ....and go to 3.50 gears..