I run a lot of open track days and with 4.10's (good for about 115mph in 4th) and end up shifting to 5th on the straights to avoid the rpm limiter. (set at 6400)
I remember in the older (88 ish) Mustangs 5th was pretty weak. Is the new transmission strong enough or should I switch to 3.73's ( good for about 135mph in 4th)?
Hope this isn't a re-post,but hey it is a chat forum!!

 

Well if your spraying, never do it in 5th. The rpm drop off % is too high to be doing that. You'll **** something up. Honestly, winding out 4th may end up a better time for you. unless you completely run out of RPMs. and if you are at that point to be running out of 4th gear, then time to get 3.73s, and that will decrease times...