ORIGINAL: Sport_Pilot
I think they replaced the carb with a smaller one on later models, they may not need the choke adapter. However it will still operate as a velocity stack and save fuel.
Actually, my TT91FS is a real fuel-miser.
My in my P51D I had a problem because the fuel tank was way too high which caused problems trying to get a decent idle with the TT91FS.
The only way I could lower the tank was to use a smaller one - so I fitted an 8oz tank I had laying about.
To my surprise, this still gives me all the flight time I could ever want, despite most of the flight being full-throttle low-passes :-)
It uses way less than my Saito 82, even though the Saito *is* tuned properly with a nice lean bottom-end and only 200RPMs rich of peak at the top (and yes, I have a velocity stack on the 82 too).