So I've been researching several of the threads regarding this and learned a few things none of which encourage me too much to go tweaking the Allison settings. I usually leave the tranny tune alone because I feel that if it's not built, the stock tranny really needs the protection of the defuels and such especially to guard it from the 5-600 hp "bolt-on" tunes I've been working with. I always knew I could make it shift "better", at the expense of reliability and possible catastrophic failure. So I haven't. But the defuels get much more noticeable / bothersome on big power applications so if I can "match" the ECM tune better to make the tranny even more reliable and feel smoother, that is what I'd like to do. So what is the basic theory in "matching" the tune, this is a little different than zeroing out shift times and bumping pressures. Thanks a lot!