Honestly how much faster can the 3.4 or 3.8L go over 115 or 120 whatever the govenor is

 

I would have to say that it should go at least to 140. Considering the steady speed increase all the way up to 125, i would say that increase would be steady up until at least 140. IMO.

I've had no problems going faster than 125 even in 4 cylinder cars.