don't drive in overdrive
don't know just *how* similar the 4T is simliar to the 4L as far as basic valve body design, but when you put the shifter in lower gears, there'* a little valve (manual shaft valve) that sends fluid to a pressure plate, which in turn tells the tranny how much line pressure to give.
what does it do?
well, the lower the gear you have selected, the more pressure it'* going to force into the tranny - giving you harder and crisper shifts.
of course, a shift kit would be nice. or if you were really daring, you could pull apart your own tranny and do a little ginding on the valve body spacer plate (Again, assuming the internals are similar enough to the 4L).
man, i'* gotta get a class on the 4T - i always wanna talk about it, but i always have to say - "if it'* similar to the ..."