i run a diablo as well...
i run the 87 octane tune, with modified parameters.
all upshifts are increased 15%
idle rpm is up 150
in gear idle is up 100
throttle response is raised 15%
tire size corrected
for the tune i run, i can the mileage (with a 33" tire) has not dropped by much....still seeing 22 on hiway runs unloaded at 85 ish
for intown, the throttle response change made a world of difference, it reacts when you THINK it should now, and slightly increase shift pressure holds the lower gear slightly longer so it isnt upshifting as soon.
drives totally different, but also as it should in my mind....i prefer the older 350th trans with a 3:73 gear ( moves when i want, feeling the shifts)
i have had this for roughly 12-15K miles...the wife just did a trip to florida ( 900miles), hasnt driven it all weak, and now says she notices the trans shifting better (i raised pressure slightly right before the trip, i had it at 10%)