I think my truck is starting to "defuel" now after a recent history of boosted launches and power braking, does this mean my stock trans is slipping c-1 / c-2 causing the defueling? Not as much black smoke now than before... typical of defueling? Ive been running stage 3 using the Accelerator... '02 D'max LB7

I think your diagnosis is correct. The TCM will sense trans slip even when you don't and defuel and pull timing.
mike