Just thought I'd post some results of some tuning/playing I did over the past few days..

i'm running an L98 with a T56 on AXXD. stock AXXD called for 200% throttle follower gain (L865D), and up to 12 steps of IAC in the iac vs. mph table. During shifts, the RPM would hang around forever (instead of coming down).

Over here here I posted about how I turned the gain down to 20% and max steps of 5 (basically, I nearly turned it off) and that I really curtailed the iac steps vs. mph table.

needless to say the RPMs no longer hung around. in fact they dropped like a rock to idle. this was fine for a while, but I got tired of having to constantly match RPMs when shifting.....the rpm would go to idle faster than I'd shift to the next gear (under typical driving conditions).

so, i revisited the topic. i discovered that the stock value for "time between IAC steps" worked fine for me;and all I needed to do was increase the iac steps vs. mph table and now I still have no RPM "hang" (it starts coming down immediately) but at a nice controlled rate. here's how i have the table set up now:

0:0
4:3
8:7
12:9
16:10
20:10
24:10
28:10
32:10
36:10
40:10
44:10
48:10
52:10
56:10
60:10
64:10

this works great! I still have the throttle follower effectively off (it just makes the throttle more "touchy" for me); but between the the "time between IAC steps" adjustment and the iac steps vs. mph you can fully control the way RPM falls off after a rev or when changing gears.