Some users reported the following:
3. Tuning notes (Gathered from multiple site)
-If deceleration backfiring occurs after loading base maps and tuning-
"Try zeroing out your 0% and 2% columns, both in the AFR table and the main fuel table, then just set your idle AFR to 13.2 (0% at 750-1250rpm) only. I think the Autotune tries to lean out the 0% and 2% columns too much because most of the time spent there is decelerating."
2008 Victory Vegas 8-Ball