Currently trading emails with John at
https://hcfautoparts.com about the GT 3:90 set up.
He sent me some graphs and will post them if ok soon.
Was the top speed on the GT about 205mph ...if so that would be about 6,000rpm in 5th?
A 3:90 would get to 7,000rpm in 5th at abut 200mph... so pretty close (but past peak power), so how would a change into 6th act on climbing past the OE factory top speed?
6th at peak power 6,400rpm = about 225mph. (too much resistance to get there id bet)
A change from 5th to 6th has a 1,200rpm rev drop (assume changing at 6,500rpm)
You have stop watch numbers like many mention like 1/4 mile out to 1 + mile and top speed.
They all get placed on a 1 dimensional piece of paper.
Feel is personal and only the neurones firing in your brain during a peak experience hold tremendous value to you (time slips are for everyone else)
So what if a stock GT gets to 150mph in x time and a 3:90 does in 2 seconds slower (just my story) but your getting more "shit yeah" out of the 3:90 as the effort or "hustle" feels dialled up v's stock.
Your friends say "Dude it's 2 seconds slower" and your face says "like I give a shit"
Imagine if Ford did offer a 3:90 from their performance division, id bet the "reviews" would have picked that as the "choice Ford performance option" v's OE daddy long legs.
It would've taken forever to sell the GT if it came with a 3:90 as the 0=60 would be closing in on 4 secs and get not near the front page attention, but really 5+ to now 15 years later it might have been even more ledgendary?
FYI .... A 3:90 is as short as the trans will go.